|A. auxiliary V-deme||ought to V|
|B. auxiliary V-tello||must V|
Both of these verbs are auxiliary only. Deme expresses mild obligation and tello expresses strong obligation. Tello is used for polite imperatives, as in: Kuno-tello=di=nu! ‘You must get the thing!’ or ‘Get the thing!’.
Deme is probably derived from da ‘go’ and the obsolete particle me ‘in’. Tello is derived from tene and the obsolete particle lo ‘up’.
Deme and tello are used with kuno to express want and need. Kuno-deme with a complement clause is ‘want to’ and kuno-tello with a complement clause is ‘need to’.
These two auxiliaries exist because as a native English speaker I cannot imagine not having them. I know of no work-arounds to expressing obligation than using ‘should/ought’ or ‘must’ (or ‘need’ or ‘got to’). I am sure there are other ways to express obligation, but I have no idea what they are or how they work. Of course, I haven’t gone looking recently for other ideas because the existing system works so well!