Or alternatively can get a good chunk of that water and blast the wretched zombies. Then he can use the extra space to slither cross the passage.

He goes nearly to full form for this, not going full size and keeping the arms to carry the stranger. But he looks like a cross between a serpent and a bird with iridescent feathers.

That gets rid of some of the water, but there must be some larger body of it on the other end of the tunnel, because it's quickly replaced. The blast does give them some breathing room from the zombies, at least- though, if he looks back a ways into the tunnel, he'll find that none of them seem to be following them outside of the cave. The horde stops on the threshold of the passage, watching- and then are hidden from view as the wall his blood had banished melts back into place. 

His passenger notices none of this, once again completely occupied by the contents of his head, still muttering indecipherably - some of the words sound somewhat familiar, so it's probably something romantic, at least, maybe even Latin? But Teddy still can't understand what he's saying, when he can even make out the words.

Teddy is still too shocked that it worked at all.

He tries to make reassuring noises at the stranger. And also to leave this place and get him to the nearest hospital. But leaving this place first.

By making his way down the tunnel, Teddy will eventually find himself out in the open air again. The passage leads out to the open water at the bottom of a high cliff, and it looks to be the middle of the night, the moon shining bright above them on a backdrop of innumerable stars. There are a few rocky outcrops in front of him where he could stop for a moment, too, if he'd like.

Yeah. He would like to do that. Also check on his passenger. "Hey, hey? Can you hear me?"

It takes a bit of prompting, but after a few moments the young man seems to recognize the change in location, and realize someone is speaking to him, and he stops in the middle of a mumbled sentence and jerks his head up to look at Teddy.

"Wha-" he coughs on the word, "I- yes, I hear you." 

"Do you know which direction to go? The nearest hospital?"

"-Saint Mungo's is in London? But I can't go there, the aurors will take me-" he stops, noticing the tail and staring at it again, "I- what- who are you? What were you doing in that place? Are you one of the defenses I won't let you take me to him-" he gropes around his robes frantically, looking for something, but his still shaky hands make the task difficult. 

Teddy restrains him with his hands, then remembering his magical powers, he glues some feathers on the hands. The stranger will find himself unable to hold anything.

"Sir... I just saved you from a bunch of walking dead," he tries not to sound like he is demanding gratitude. "I am Teddy, I don't know what is going on. I was somewhere else fighting a snake monster, and then I was in that cave."

He barely even notices that the feathers are making it harder, it's already hard enough, and he gives up on the attempt after a moment, distracted by the first words he'd said, looking up at Teddy with wide, frightened eyes. His hair falls back out of his eyes and Teddy gets his first good look at his features, then - he looks young, maybe nineteen at most. 

"The inferi, are they still coming?" 

"The undead? They stayed back in the cave. Didn't want to cross the threshold."

"Good," he relaxes a bit, "Good... I..." he blinks up at Teddy, his eyes starting to go distant and haunted, and then he shakes his head, grimacing, "That potion..." he mutters. "I'm sorry, I'm not very- you said you- don't know how you got there?"

"No... I was called to deal with a monster attack, got there and there was a snake thing with a mirror for a face. I tackled it and then I was here. You mentioned London? This is in Britain then?"

"Yes... I have never heard of such a creature..." he gives a sharp shake of the head, trying to keep his attention on the world around him a little longer, "I- will call my servant," he decides, "He can take us somewhere safe. I don't think I can- that potion..." he trails off again, starting to shiver once more as his eyes drift to the right of Teddy's face, becoming unfocused. 

He is wondering if this guy is sufficiently alright to talk. Teddy gives the mildest slap to the stranger's face. A pat really. "Hey, hey, stay with me."

He breaths in sharply, hand jerking up to touch his cheek, "-apologies, I'm not-" he huffs, "This is ridiculous- Kreacher!" 

There's a sharp crack! And then, suddenly, they are sharing their little rock with another... being. Small, wrinkled, greyish-green and spindly, the being is wearing a loincloth made out of a tea cozy and nothing else, and immediately upon appearing they throw their tiny body at the strangers feet with a cry of, "Master Regulus! You is being alive!" And start sobbing into his robes. 

Gah. This causes Teddy's feathers to hackle. Remarkably cat-like for something that is three kinds of creatures none of which is cat-like.

Calm down.

"...Hi?"

Kreacher is too busy crying to reply to Teddy's greeting right away.

Regulus sets a hand on Kreacher's back and tries to keep focusing for a little while longer, "Yes- Kreacher I need you to take us to the safe house..." 

"-Ye-yes, Master Regulus-" Kreacher pulls himself together enough to look up at Teddy, "Who is it? Rescued Master Regulus, it did?"

"My name is Teddy. I am a he." He changes, so he is mostly human, wearing muggle-looking jeans clothes, albeit reinforced ones. Only his arms are still feathery.

"Hmmmmm..." the little being grumbles up at him, suspicious.

"Kreacher. Safe house," Regulus repeats.