I suppose the thought process behind this one would be, either:
- The Player gets to name them when the game starts/in other runs so that would mean they would be still around;
- As Flowey confesses to calling them, Chara later associates that event with their return.
That is, if Chara is to be trusted. Their OG dialogue could be read as to imply something similar:
As they immediately associate "the power that awoke them" to the "human soul" and its "determination".
TL;DR: Chara never actually resets, and isn't a megalomaniac before a genocide run. Frisk doesn't want to reset. So, who is resetting in a pure pacifict run?
Well, for one, I still feel Deltarune certainly tips the scales towards the player for the simple reason that it gives a more in-depth explanation and I don't think it's controversial to say that the DT player is the UT player (every time you can outright reference UT as an entity possessing Kris; toby saying you should play UT before you player DR, etc.).
Chara isn't the one resetting, ever. Even if they have the power to do it, they aren't the ones who want to go back on whatever ending you get and reset, that choice is always left up to you, and never just automatically happens, unlike the times Chara walks or attacks without
your input. But if the "your" making the choice isn't Frisk - who wants to live their life, and it isn't Chara - who finds completionism perverse and only came to appreciate megalomania
after the Genocide Run, then there has to be a third party here.
Plus, the Chara presents their dialogue can be taken to mean that they are talking to the player, and not Frisk. Besides the more obvious one where they claim to be the demon who comes when you call their name, with their revival starting when the player names them and fall into the underground, there is also their use of quotations to refer to things that were not their own but the player's.
My "human soul"...
My "determination"...
After that, quotations are used again, this time for their name.
Certainly, not the most hard hitting proof, but I think it's worth pointing out.
There is a level of ambiguity, but I think it's fair to say that claiming the player is the one normally controlling Frisk is at least
as fair an interpretation as saying Chara is the one always controlling them.