What you do when they're injured.

Merlin-
You make him lay in bed all day. You even tell Arthur and deal with him. Merlin hates having to lay in bed, so you help him practice spells. You, like Merlin, have magic but aren't a Druid. Depends if it sickness or injury you kiss.

Arthur-
You hang out with him all day. You put up with his moaning and him constantly saying he's bored. Arthur had no patience for staying in bed. But with you there it wasn't that bad.

Mordred-
You talked to him into Gauis' chambers. He typically has to stay there. You can openly talk about being a Druid with him because both Gauis and Merlin know. Whenever people aren't looking you kiss him on the cheeks if he's sick and on the lips is he's injured.