Leon definitely suspected that Tassera wanted more than just a stroll through Watchtower Port; there was certainly something else afoot, but he didn't care to delve into it.
He now only wanted to completely resolve the matter of migration, resolving not to involve himself in such troublesome affairs.
Watchtower Port was well-located, but not perfect; in the future, he would encounter places more suitable for nesting... There's no rule that a dragon can only have one lair; rather, it's normal for an Adult Dragon to have several lairs. If he encountered a good location next time, starting anew would be better than moving.
