They get injured

Kirk:
You fuss over him while he's in the sick bay. He always assures you he's fine, but you know he's lying. Scans don't lie.

Chekov:
You take care of him and encourage him to rest. He keeps protesting, saying he doesn't want to make you work, but you insist. He secretly likes the attention.

Spock:
Sense being injured or sick is something that doesn't happen often to him, you need to tell him all his signs every hour. Every once in a while you'll kiss him. Your excuse is that on Earth, the phrase is "I'll kiss it and make it better" He didn't get it at first, thought it was illogical, but eventually caught on.

McCoy:
He hates when he's injured because he's usually the Doctor. He hates being taken care of.

Sulu:
You sit with him in his room or the sickbay. If its his room, you cuddle and watch his favorite movies. If its the sick bay you, read his favorite books with him.