If you found him at such a late stage, it's possible he's parasitized or something like that. Sometimes you can't even know until something looks wrong with the chrysalis, or it turns black before it's supposed to, etc.

Hopefully, though, he's just getting ready to pupate. It's a complicated process. I have never raised this particular kind of butterfly so have no idea how long they spend in "J" formation, but it can take a day or a little more before they actually shed that last skin.

Keep us posted. :)

Hey, bernergrrl! Well, i had to go out earlier for a few hours and when i returned i noticed he had formed a chrysalis! However, it's a lot darker than it should be :( it looks as though it's infected, so i think I'm just going to leave it a couple days just in case but if it gets any darker or the abdomen gets looser I'll have to destroy it :(

Leave it alone. If it's infected, you will know within a week. If not, you will be the proud caretaker of something that belongs here. :)