All he needs are his books. Doesn't like leaving the Loremaster's Tree (while in the Valley), however he doesn't overload himself with work. He spends a good deal of time watching the shenanigans in the Artist's Tree to the south, and sunbathing on its limbs.
Euncil is the kind of dragon you find in odd places. He can survive in pretty much any climate because he really can be at home in any place (even though the Valley is obviously his preferred abode), although he isn't very fond of Plague flight. He isn't known to wander without permission, though, so chances are Ayella sent him off to gather some sort of intel, most likely of the sort that needs a gentle hand and good conversation to withdraw.