His arm wasn't the only thing the Galra changed. They also gave him certain... needs. Shiro learns to make it work for him.

“I want you to bitch me.” Tim reacted to the word so strongly he nearly fell off his chair. “Kon you- you can't say that!” It wasn't a word one should bring up in polite company, Tim had learned early on. Kon rolled his eyes emphatically. “Fine. I want you to help me transition my dynamic into one that more closely resembles how I feel inside. Happy?”