It's better than medicine! It's... It's just a different sort of healing. People do it all the time. It's not Bilbo's fault if Thorin's folk are more repressed and-- The kiss catches him off guard. He'd not been expecting it. The process was relieve Thorin's stress, wash up, get the documents signed, have some tea on the secret door's terrace! There'd been nothing about kissing on the program!

Nothing! In fact, Bilbo would have noticed! He wrote the schedule!

Sorry Thorin. That nice stroking has suddenly stopped as Bilbo's forehead wrinkles between his eyebrows and he finds himself not sure where to put his other hand. Jaw? Chest? Hair?

Oh no, and Thorin's stroking his hair-- It's just about too much and Bilbo leans away. "W-What are you doing?!"

Perfectly normal to jerk your king off, but kiss him? Oooh no.