"Hunting for someone to bite and-or actually biting someone."

"The alarm's theoretically supposed to warn you before you get to that point."

"Yeah, but Willow raised the point that it wouldn't actually stop me if I got past that point without noticing beforehand."

"Hmm... So you'd kinda need a live-in spotter."

"Unless it gets to be enough of a habit?" he shrugs. "And long-term, if we can work out a schedule, like I feed for thirty seconds per day and would get peckish after about twenty-six hours, then I probably wouldn't need someone live-in so long as we made sure not to let me get peckish."

"We should look up what human blood replacement rate is."

Theo does so! "Apparently blood donation is usually about a pint, which is like ten percent of your blood volume, and you can donate every twelve to sixteen weeks."

"...hm. I think I probably have more blood in general when I'm a boy, but even so that doesn't look terribly promising unless you need to feed 'basically never.'"

"Yeah, it's not looking promising if my blood doesn't heal it up."

"Even if it does, it'd have to heal up more than you had to consume to produce it in the first place, and we're back at the infinite blood hack. I wonder if there's a way to measure how much blood I currently have in my body, even approximately."

Shrug. "Blood pressure you could at least do it relatively, work out how long it takes to get back to a state you were at before? But I don't know if you can measure it all, no – maybe by like, a CT or something, but we don't have access to one unless I try swaying people."

"...let's try to minimize the amount of mind control going on."

"Yeah, agreed."

"Is there a known relationship between BP and relative blood quantity? Or average BP or something."

He does a bit more googling and then reports, "Apparently blood viscosity can also change and mess with the results, and when you replenish blood you gain back certain components faster than others – red blood cells come in later – which changes the viscosity itself, so it doesn't seem like there's an easy relationship without directly testing your blood viscosity and your blood pressure and then seeing if there's some number for the relative blood quantity." Pause. "But it also depends on your cardiac output, which would mess with the systolic blood pressure? So I'm guessing we'd have to use diastolic and even then I'm not sure it'd give a direct relationship."

"Well, but even if it was an approximate relationship, it'd be pretty useful."

He looks a bit more, pauses for the alarm, then continues. "Can't find any formulae for it. I can find things for cardiac output, relying on your heart rate and stroke volume, which really isn't that complicated – the amount of blood your heart processes per minute is the number of beats per minute multiplied by the amount of blood per beat." Eyeroll. "But actually calculating the amount of blood you have based off the pressure in your arteries doesn't seem to work – it depends on how fast your heart is pumping the blood around and how viscous your blood is, would only give a proportion, and there don't seem to be any clear formulae or example bits of data that I can find."

"...if this wasn't an absurd waste of time I'd want to figure it out. Also that alarm's gonna be annoying."

Shrug. "Anyway, I expect some people do know, probably, but I can't find anything quickly while looking so you might need to, like, look in some medical library or ask some professor at a university or something."

"It's probably easier to just bleed into a cup and, like, measure."

"… And measure the blood pressure versus the amount of blood lost, you mean? Since we can't actually directly measure the whole amount of blood." Pause. "And did I mention that different components of blood are regenerated at different rates? The red blood cells get back later on so you might not be okay even if the blood pressure seems about back to normal."

"No, I mean, people have approximately a certain amount of blood on average, they can donate more-or-less a certain other amount every x days safely, we add a safety margin and just figure it out."

"… It's about a pint every twelve to sixteen weeks?"

"Yeah, exactly, we don't need to figure out how much blood anyone has in their body here, you get out the safe amount a few times and see how that feels, then start drinking some of Theo's blood and see how much better it feels and after how long, and then extrapolate."

"So, go back to the idea of 'hope that it actually does heal it properly'? Yeah, this thing seems like too much effort and it's in preparation of the other idea not working, which we don't even know it won't." Shrug. "Besides, I can still eat animals in the meantime."