The kid was going through a lot, and while Bones wasn't going to be mean or tell him to buck up, he wasn't exactly gentle either. Bones had never been a particularly compassionate sort, even before his family died, but without his wife around to reign him in, Bones came off as callous and harsh. He couldn't help it. Everyone had hardships. Everyone lost something in this war. Still, he had every reason to be this angry. He could see a lot of Rook in this boy, but maybe it wasn't necessarily a bad thing.
"That's what the Death Eaters do, kid," he told him, leaning against the table and watching Harry closely. "Every person you've talked to who remembers you as Harry Potter has lost something by their hand. Family members, friends, a sense of who they are... whatever it was, we've lost things. Some are just better at hiding it than others."
He sighed and sat fully on the table then, keeping close enough to Harry to make sure he didn't open the damn journal again. "Spoilers, you can't be him," Bones told him, but continued before Harry could protest. "That's not who you are anymore. Even if you get your memories back, you spent months as someone else and that's going to change you. Everything changes you. So focus less on the past and live in the future. Forget what people expect. Forget Alec Dolohov or Harry Potter. Who do you want to be?"