"Why do Ludwigs physical needs and conditions changer with each alter, I mean how does the body in Fritz's case need help seeing and hearing while Ludwig the host, doesn't, even thought it's the same body?" - glorious-porpoise2

This is actually a very good question! Psychobiological differences are known to occur pretty frequently but professionals don't really know why. Not much is known about why these things happen, at least I didn't find much information in my research, but I will share what I do know with ya'll. My hypothesis is that these issues occur in the brain rather than the eyes or ears, so when another alter fronts and the brain "changes", these issues come with them, if that makes sense.

Alters having different genders than the host, speaking different languages, having different accents, different handwriting styles, different talents, I even saw this one documentary where a woman with DID, who was blind, had a little(these are alters who are children, usually under the age of 12 but the requirements vary between systems) who could see just fine are all known to occur.

Sometimes these differences are caused by the trauma that caused the DID or other traumatic events that caused the alters. For example, the system from the YT channel Multiplicity & Me(I used this channel for most of my research. They mostly talk about what it's like living with DID) has hinted at having sexually based trauma. As a result, all of her alters are male because as a child she had the thought that "if I were a boy, this wouldn't have happened to me". Abusers telling their victims "Don't talk" can result in mute alters while abusers telling their victims "you didn't see anything" can result in blind alters. Fritz's issues don't really directly relate to traumatic experiences though.

Actually, the other alters have hearing issues too, they just aren't as severe. The others use spells that help their hearing rather than actual aids. Fritz can't cast these spells because his magic is so erratic and uncontrollable. Kooky won't cast the spell for him because he believes it's just delaying the inevitable, which is technically true because Fritz eventually goes deaf later in life.

Like I said before, it's not really yet known why these things occur. There's a lot that's still unknown about DID, it only just recently became acknowledged as a real disorder in 1980, and getting professionally diagnosed takes at least 7 years of therapy. It's a very...mysterious disorder.

I hope this answer made sense, if you decide to conduct your own reserach on the matter, I'd like to know if you find an answer! Have a nice night/day everyone!