I second jorats. Neuter helped my aggressive ones.
How old is your boy? Do you have other rats? Is he alone, or in a group? Can you remove him from the cage, and see if he still bites, or lunges? What does he look like before he bites you? Make sure you wash your hands with unscented soap before trying to handle him. Also if you have handled other rats, or animals, maybe try changing your shirt, and washing any parts of your arms or hands that have come in contact with them before approaching him. There are lots of other good tips on www.joinrats.com to help with socialization. Most importantly, DON'T give up on him! There are ways to turn around the biters. I've had my fair share of them, and it's not fun, but very rewarding when you see progress with them.
As for the bites, make sure to always wash them with antibacterial soap, and warm water, put neosporin on them, and take some ibuprofen to help with swelling.
Befor he bites he tenses up and is still. he just turned one on Jan 25 also when I try to take him out of the cage with my hands he bites the only way to get him out is to lure him into a hut or hammock I give him free roam and he still acts untrusting he’s from a good breeder though when I chose him he did jump out of my hands and nibble me a few times I should have thought of what that is a sign for in his future
He lives in a group of 6 him and his 2 other brothers are new and my 3 original boys dewie actually bites the other rats too and he injured alfies eye but alfie is healing well and is eating and drinking good.