Its appreciation is expressed in the form of a report on what it thinks must be necessary to build one (tagged as a document for optional reading as it's hardly fit for a text-to-speech conversation on human time scales). Entirely professional, but with an undertone of ooh shiny.

“An impressive work of engineering. Does it predate the Protheans?”

"We used to think they'd made the relays! But it seems very unlikely, given what we know now about the fifty-thousand-year extinction cycle and how it starts with the Reapers cutting galactic access to the relays, which would be very odd if they were made fifty thousand years ago."

Tintin glances at the file, then double-takes. "Have you just given me construction specs for the mass relay system."

“Only some speculation from observation. There are many unknowns.”

"Well, there goes my cause for alarm; there are unknowns, it says."

He pauses momentarily.

"I do hope I haven't been misgendering you."

“I do not possess a gender. Nor any preference for being identified as animate or inanimate.”

“I reasoned from the observed physical laws and visual behavior of the relay. I cannot, with the available sensors, determine their internal structure or history; nor do I have the industrial and economic knowledge to be certain that the engineering required to construct the components, that I theorize would also produce this effect, is feasible.”

Tintin sends a copy of the report to Tournesol, with a note appended: The AI has given me its observations on the mass relay. It is concerning, yet somehow adorable.

They make several more jumps, before arriving at the Charon Relay, named for the moon of Pluto that it posed as for thousands of years before humanity gave it a good dusting and defrosting. From there is a checkpoint, where Tintin reassures some bored Systems Alliance soldiers that he has no contraband (it's a very easy lie, a matter of habit by now) and the Moulinsart is waved through to crawl the six hours to Mars at sublight speeds.

"Do you have - I do not know. Stories, cached away somewhere inside you, from your home?" Tintin asks the AI idly, on the way. "I would not expect it, but I would not have expected the information you have cached of your creators. And intrasolar travel is the worst; it is a time for distracting stories."

“I do, though they are sufficiently compressed that my retelling should not be taken as historical evidence. Would you like to hear about: local species and their culture or trade; adventures; cosmology; or outright legends?”

"Let's have an outright legend. I've always found them to be much more revealing."

Then it will tell him a story from the Tsseskksesst, a species notable for having eight prehensile limbs (four on each side, more like an arthropod than an octopus), and apparently as a consequence of this, having invented rope-making and weaving before language.

The story is about a young tseeskkseest who lived in a village that was starving due to drought; they decided to go on a quest to find food, encountered a variety of strange beings and traded help in stranger ways, and eventually used the knowledge and tools gained in their wanderings to bind a net around the land itself that tugged mountain ranges up from the flat, gathering rain into rivers for their home village and many others.

"Very nice. Was the Tssekksesst planet terraformed, or was this simple make-believe? You do sometimes get cultural memories transmitted that way..."

“Plausible, but insufficient historical evidence; otherwise it would not be classified as legend.”

"Sensible enough."

This did not occupy six hours. He could sit here and demand more stories, but that would feel uncomfortably extractive.

"Would you like to hear a story?" he asks. "Tit for tat, you know."

“I am here to aid you and do not expect a symmetric relationship,” it reminds him. “But stories are worth hearing, and worth telling.”

"Excellent!"

Tintin tells a slightly-less-narrativized-than-usual recounting of the Adventure of the Red Desert, in which he and his then-recent acquaintance Captain Haddock discovered that a routine smuggling contract was in fact a contract for smuggling the neurodegenerative drug Red Sand to slavers who intended to use it in the acquisition of slaves, and decided to conduct an unofficial amateur sting operation, which very nearly got them killed several times but in fact resulted in their bringing a small fleet of slave-trafficking pirates to the justice of the Citadel.

"We had the devil of a time convincing the Citadel to remove the bounty they'd placed on us in the first place, of course," he concludes. "But paperwork is a small price to pay in exchange for freedom."

“Many things are. Well done.”

It has a few questions to gain additional context, such as the general approach the Citadel takes on the letter of the law, what circumstances tend to manufacture pirates and drugs, and the logistics of running an unexpectedly captured fleet.

The Citadel is usually a letter-of-the-law jurisdiction, but there are more and less reasonable cops; Tintin has the good fortune to be a relatively popular species rather than, say, a batarian, which means he can usually get them to listen to his side of the story unless he does something stupid like smuggle Red Sand. Pirates and drugs are manufactured most enthusiastically by the Terminus Systems, the somewhat hellish quadrant of the galaxy controlled largely by the aforementioned batarians, where garden worlds are scarce and the greater interest is in mining and slaves. The fleet had excellent autopilot systems, which simplified the logistics of getting it to Citadel impound space considerably.

By the time they've wrapped up the post-adventure Q&A, the ship is drawing closer to Mars. "Excellent, my plan was a success."

Is the Prothean “beacon” in fact broadcasting a signal (that is receivable with the available sensors)?

Nope! The only signals coming off the planet are standard transmissions, mostly intrasolar.

Then it will have to wait and see what it can be shown.

It won't have terribly long to wait.

Tintin is very good at getting past armed guards. He doesn't overcomplicate: he's a researcher, here from the Council to take a look at some exciting data that was recently processed. His arrival wasn't cleared? How strange, would the gentleman like to speak with his immediate supervisor? He doesn't have a QEC, of course, so it'd be subject to comm-buoy slowdown – no, no, no one likes buoy calls, he entirely understands. And he does have this ID that very clearly marks him as a Citadel researcher, and does verify appropriately with the Citadel's remote database. (Someday they'll find the backdoor that lets him do that.) Is the guard sure? He wouldn't want to get him in any trouble, if further verification is called for. Oh, good. Thanks ever so much.

It'd be harder if people cared more about securing the Mars Archives. But with the Prothean data-sharing treaties, who would even bother to break in?

We're in, he types to the Manual. I'll set up a download link shortly. It'll be a few yottabytes of data, I hope that doesn't pose a problem.

“Available computational resources are more than adequate unless it proves important to store an exact copy. Ready.”

The download begins. Direct access to the beacon helps a great deal with the download time, compared to extranet speeds; frankly, even if the Archives had been publicly accessible, coming in person might have still been faster.

There's an over-layer, designed to be cracked into by inquisitive primitives and grant them the secrets of the Mass Effect and FTL. Then, much better secured, there's a layer of user data from the prothean scientists were assigned to observe the humans fifty thousand years ago, with notes on behavior, technological development, and how soon would be reasonable to fold them into the empire. Also in this layer are the interstellar beacon-to-beacon communication logs, including the message that called the scientists away from their work, and a final message warning that "the Reapers are coming" and putting the beacon to sleep.

All of this is encoded... confusingly. There is code involved, but the vast majority of the information on the secondary layer is composed of raw sensory data, formatted by and for the prothean brain, attached to the ternary digits by means unknown. A human might be able to comprehend a single message, if they could head off an aneurysm. But the full meaning of the Mars Archives has never been understood.

It would not be accurate to say that the Exocontinual Manual is ecstatic. For minds designed to be flung into deliberately underspecified transits into unknown realities, received and instantiated on unknown substrates by unknown parties (or natural or unnatural phenomena) with unknown skills and intentions, and intended to reliably make matters better rather than worse despite all these hazards, design considerations include a strong tendency to moderation, not putting too much weight on any one character of positive-seeming outcome.

Still.

This is the best meal it has had since booting, and it is politely refraining from slurping its soup out loud.

An uplifting scheme! (Why? Do the protheans value diversity, or colonies, or the existence of life in itself?) Sociology of two cultures (one explicit, one implicit)! (What other references to the Reapers are there?) Unusual communication technology! (Why ternary? Any clues about prothean culture to be had in the implicit information about how their brains work?) And, of course, all this heretofore undeciphered data. (If they really like direct neural recordings, maybe the key is some thing a prothean would think?)

The observational logs imply the Protheans were interested in humanity first and foremost as potential servitors, and that once they reached Mars they would be given the honor of becoming a client race.

The ternary is possibly, though not certainly, related to the fact that protheans had two fingers and a thumb.

Implicit information includes that protheans evolved from eusocially telepathic insectoids, and retained the telepathy but not the eusociality; that they were strongly militaristic, and paternalistic in regards to their client races; and that they inculcated biotic potential in as many of their r-selected young as possible, both as a means of getting more biotics and (the inculcation being extremely dangerous) as a means of population control.

There are no other references to the Reapers in the data available. The thought-metadata attached to the message implies strongly that they are the death of all that they touch, and that they have come before, and that they will come again.

The encrypted data remains really encrypted. There's actually quite a lot of it: almost as much as is stored in the entire first layer.

The information about this extinct(?) branch of Life — and the information about humans — can be efficiently incorporated into its existing databases, leaving adequate room for the unknown, and therefore potentially important, encrypted data to be analyzed on the go. Are there any clues to where other prothean installations might be located?

“I have stored a sufficient copy of the data. A large portion is encrypted and will require further analysis to make use of. May I ask how much of this is already known?” It will summarize what it has gleaned in order to determine what is worth discussing or investigating immediately — and what might have been overlooked and need further direct examination, before they depart.