This is an unstructured rant!! TW for lots of gore and unpleasant imagery
I think Lyf goes through a metamorphosis. While he survives the Bifrost and escapes the Yggdrasil system, he's hardly unscathed. Seeing the effects of the great old ones and directly staring into the eyes of Yog-Sothoth changes him in a way I think about often.
I think he very much could've died, though due to the nature of his survival and the fact he is now rapidly travelling through the cosmos, with the knowledge of the great old ones, they keep him alive. He's insistently their unknowing vessel, subconsciously spreading their powers further and further into the galaxy.
Anyway onto his metamorphosis. It starts off small. Mild headaches and aches of the body as his cells and skin struggle to compute with the sudden environment shift that happened on Midgard. Pains that only grow. I like to think being around him gives people headaches too. A sort of unexplainable crawl of the skin, an itch that doesn't go away. Taking inspiration from the Dunwich horror I like to imagine animals start to resent him, dogs growing aggressive in fear, rats and other urban animals fleeing weeks before he arrives. People start to associate him with the dread inducing call of a Whippoorwill.
After he leaves people tend to feel ill, falling sick, feeling like their insides are melting. Depending on how long they were around him it ranges from a mild headache to multiple organs shutting off as the aroma of his presence melts the body from the inside out. No matter what Lyf does he cannot stop what he causes, instead opting to keep travelling, only continuing the great old one's plan.
Now on to his body.
The headaches are constant, though sometimes they're weaker than other days, allowing him to think. Other days they're so bad he fears his brain will explode. Cracks start to form, his skin rotting and starting to fall off. Bald patches in his hair grow as the skin grows weaker. There's an unbearable itch beneath his skin that he's never able to get rid of no matter how hard he scratches. His bones ache, body sweats with thickening pale mucus, obviously he's sick, throwing up rather a lot. His sick is black and has the residue of oil, staining whatever surface it touches. Perhaps by occasion, eyes glance back, hidden in the inky black mucus.
Additionally taking inspiration from Wilbur Whatley, he gets the whole tendrils in the stomach thing. I like to think he binds them to still appear somewhat normal.
Whenever he gets cut or hurt by any nature it's healed. Despite his body rapidly trying to die he cannot, the old ones will not let him. The rotting is a reflection of his body unable to keep up with his mind. If he were to get a deep cut black tendrils would morph out of his skin, wrapping it air tight. Over the next few days it'll remain, slowly melting away his skin, bones, veins as it rebuilds whatever is hurt back from square one. If someone were to somehow get it away from his skin then they'd be met with a strong acid and a significant lack of skin underneath.
Anyway I wanna slowly explain all my Lyf lore because theres alot!! I think I'll just do unstructured rant posts like this, doubt anyone will care much but if anything it's useful to have all my information together :)!!!