Exactly; POOF! or whatever other onomatopoeic word goes best with bad-ass ninjas appearing and disappearing from a cloud of smoke.

Lets be honest about companions. On the one hand, they are great; they can kick some serious ass, draw attention away from you and carry you [censored]. On the other hand however.... They are dumber than a bag of brick ferrets. They always get lost, because they can't follow you while you take the classic 'bethesda-game-shortcuts' (hopping diagonally up mountains). So why not get rid of the whole following thing?

They could appear as soon as [censored] starts to go down. POOF! a big cloud of smoke and there they are. Could even be a power you get after hiring one/commanding one to follow you.

Like?

Why don't you simply get some summoning spell?

Or do Sanguines quest, you get Sanguine's rose as a prize, a nice staff which summons a Daedra. Exactly the thing you are looking for.

Yeah my dremora lord *bamfs* in when ever I want with my summon spell. But he literally chopped my head off last night when I was training on him

Well, if you want to have a completely nonsensical companion system, sure.

I gave up on the "bethesda shortcuts" when I struggled climbing a mountain, only to realize I didn't wnat to go this way at all. Then a cat killed me.
However, yeah. I guess it should be possible to mod once the tools are out. My problem with the companions isn't that they can't climb mountains, but that sometimes they don't seem to understand how stairs work...