There's increasingly more Thygruns in this particular paradox. If they leave the timeless palace, they age, and since he wanted immortality, he doesn't want to leave. If there was a first Thygrun, I imagine he spent the initial 100 year cycle realising what a pickle he was in and going through the palace library [learning to read properly].

Of course Thygrun ignores Thygrun and now there's two of him. The one with the greater seniority can teach the younger what he's learned - with a decade's worth of opposition. As an extra wrinkle, Thygrun can only go through the portal to Start Position once, hence trying to teach the new Thygrun all the stuff before the century is up.

It just gets increasingly complicated from there.

Sooner or later, Thygrun will realise that this is a monkey trap and let go of that which he prizes.