It strikes me as unusual that he lets you hold him without biting but won’t let you hand feed him and he lunges at you when you pick up his poo, when was the last time he had a check up? Maybe he has an issue with his sight or tooth issues?
Always approach a nervous rabbit from the side as they cannot see in front of them (and even less if they can’t see much)
It could also be that he’s territorial and it’s hard to identify where aggression comes from. Maybe a check up can rule that out so you know that it’s behavioural. Hope this helps xxx

Well that rules out any obvious problems
Is he a rescue or did you get him as a baby?

Having read his background he is probably just misunderstanding you and your body language. Although you’ve done nothing wrong he’s probably learnt to bite after having his previous owners keep him in a cage most of the time with no exercise or entertainment which makes a rabbit grumpy and afraid. When someone bothers him he probably bit them and they then left him alone and the threat has gone away. He is probably not neutered too and the smell of another rabbit makes him territorial which is why he’s pooping everywhere and weird about you being in his territory. (Rabbits poop everywhere to claim a space). First step: get him neutered. The marking will decrease within weeks and he will be calmer and less territorial. In the meantime start again with all communication. Sit in the floor during his playtime with pellets in your hand and wait for him to come to you (it’s boring but it works) don’t move look at him or make a noise. After a few sessions talk to him softly when he’s eating the pellets. After a few more make slight movements. When he’s confident then you can pet him. Don’t pick him up at all until he’s a lot better with you then as long as he’s happy to be held you may go back to giving him cuddles. It seems like going back to square one but it’ll help so much and make him so much happier in the long term.
Before handling him you must also wash your hands and get rid of any smell from the other rabbit as this may also be why he is biting!
I hope this advice helps you. Let me know how Bambi gets on xxx

Hannaroo brings up some excellent points and advice. Once I read the background on your bun that is exactly what I was thinking. I can’t blame him for being frightened if he spent the beginning of his life in a hutch being ignored. It sounds like a learned behavior. I agree also that he is being territorial if you smell like your other bun. On the positive side, the fact that he lets you hold him now seems to mean that he is a bit conflicted in his feelings and that he wants to trust you but doesn’t fully quite yet. I see that they are already neutered so that is great and behavior probably isn’t tied to hormones. Also, he is still young and he may decide that he doesn’t like being picked up as he gets older so don’t be surprised about that. That being said, I’ve read most buns start resisting handling around 10/12 weeks so you might be lucky and he could be a rare cuddle bug. I think it will just take some time. From everything I’ve learned thus far your case sounds far from hopeless. I’ve heard a lot worse. I think you are on the right track and like H said, a little back tracking to gain trust certainly is a good idea.

No worries. Taking it slow will work but it just takes time. It may take a few more weeks for Bambi’s hormones to settle then his litter hormones will improve
As far as playtime goes they probably will be able to be bonded one day but wait until your ready as some take only 3 days to bond and others take up to a year (although that’s quite rare) so when you feel ready check out our bonding section and ask as many questions as you want! We have some great members who have bonded 4 or 5 rabbits at a time and others who can I’ve you some great advice good luck with Bambi it sounds as though he has a happy life and freedom ahead of him xxx

Are they allowed out for playtime in the same area? My guess is that it’s a hormone/territory thing. Smelling the other bunny is probably making his hormones go crazy, especially with the recent neuter.

I’ve been bitten quite badly twice by my super sweet neutered buns, both having to do with territory issues.