How do I change characters in The Ruins of Sarudnahk?

Solution 1:

No, there is no option to change characters dynamically, as stated on Gamefaqs forums:

I'm pretty sure there's no way to change again.

and Steam forums:

I don't think you can change it once you have chosen.

[...]

Yeah, I just restarted the game.

However, Steam user Link2434 said:

If you chose Kaeris, don't worry; you'll later be able to come back as Clink

So surely no option to change directly, but "maybe" another chance later in the game.