[All Mirio wants is for Tamaki to feel better about life, okay. If handholding is what needs to happen to get him there then he'll hold his hand for the rest of time, thank you very much.

Tamaki is totally allowed to make this a mutual thing too, especially since Mirio isn't letting go...

He does see the way Tamaki looks at the fountain again, Mirio's complexion paling.]

...if we're expected to be kept here for any amount of time, I'm sure we'll have something better to drink than stagnant water from a rusty fountain.

[He doesn't want you to be poisoned??]