Hey, I am pretty sure Frisk's determination isn't infinite actually. It says on his page under weaknesses that he will eventually give up.
It also says that it is extremely unlikely and that weakness only comes from other souls as all of them gave up. And none of them is actually comparable to Frisk. Even Asriel talks about Frisk "never gives up" and mentions how they are exceptional. He also considers killing Frisk 1,000,000 times over as a real possibility. Not to mention, at the peak determination, they get to 2-B durability. Considering an average human caps around 8-B, that's infinities upon infinities difference. Pretty much infinity determination you speak of. (Though it is not exactly at this key. But still should downscale to some degree)
Also read this part of the Weaknesses section "Someone with equal and higher amounts of Determination (as it exists in Undertale) will result in their ability to SAVE and LOAD being disabled"
Subaru's willpower is at the very worst comparable to Frisk, and at the best his is LEAGUES greater than his.
FYI while it is still related to conventional willpower, "Determination" is a substance found in Undertale. Subaru doesn't have that. Not to mention, Frisk can create "Last Dream" which is described as "The goal of Determination." This is literally the highest possible level of determination.
I would say there's pretty much no way he's influencing Subaru in any meaningful way.
And why not exactly? The last time I checked, Subaru was a good guy. I don't see why he wouldn't be willing to have a peaceful solution.
Such as getting Beatrice to be his contract spirit in the first place. Which no one in 400 years could do. And was basically so impossible that Roswaal (A genius who has been alive for 400 years and set up Arc 4 to be completely against Subaru), Echidna (The literal witch of greed who has pretty much endless knowledge about the world), and the gospels (Which can predict the future, even through most of Subaru's resets) could not predict that outcome. It basically wasn't even supposed to exist as a possibility.
Frisk can befriend an entire race that was previously hostile to them. Some of the most notable examples include Mettaton (who was originally designed as a human eradication device), Undyne (who was hell-bent on killing a human most out of anyone and is the only monster to have determination), and Sans (Who was initially completely nihilistic to point where slaughtering his brother and half of Underground still wouldn't make him take action). The only being Frisk couldn't befriend was Omega Flowey who had LV almost 500 times that of maximum value. Even then, Frisk could make still make other human souls inside switch sides by merely calling for their help (Heck, they can befriend somebody by just knocking on the door or make someone addicted to them by clapping). Frisk later on can make Flowey, a soulless being, have a complete breakdown. And by the end of True Pacifist, he is impacted enough to completely change his way.
An unpredictable future has got nothing on Frisk as well. The ability to SAVE is multiple times mentioned to be the power to change fate and it is even mentioned as such by Toby Fox. "Fate" itself is a prevailing theme both in Undertale and Deltarune with the outcome never changing in the latter regardless of what you do, contrasting Undertale. It is not just that. Flowey mentions that he has seen every possible outcome ever and sees everything as predictable with the only exception being Frisk (Flowey believes them to be Chara at this point) whom he never could predict. It is also mentioned in True Pacifist Route with Asriel saying how Frisk is special and the only one fun to play around.
Or getting almost every main girl in the series to become fond of him. Including those such as Echidna who have been alive for hundreds of years and have had people like Roswaal obsessing over them.
Seriously?
The monsters he is influencing are much easier to influence than everyone I've brought up for Subaru though.
That is still an entire civilization and the whole game happens in a day.
Not to mention, if you want to bring up Subaru needing RBD to do social influencing stuff... What about Frisk? He constantly has to SAVE and LOAD before he can get to those outcomes. Many many times more than Subaru needs to influence people
Honestly, I feel like you are a bit biased. There is no canonical number for how many times Frisk needed to LOAD. It can be 0 times or a billion times. But Frisk canonically can do all of them in the first try considering there are corresponding dialogues.
Besides that, Frisk's capability to read people is on another level. "Check" alone can provide information about one's hobbies, mind-set, behavior, lifestyle, etc. And their ability alongside narration borders on mind reading. I am pretty sure there are seldom characters in fiction who can tell that a quiche is psychologically damaged just by looking at it. Or some other examples:
Papyrus remembered a bad joke Sans told and is frowning.
Glyde is thinking of new slang for the word "cool." Like "freakadacious"
By the way if this means that Subaru's willpower/determination will literally nullify Frisk's main abilities,
It will not as explained above.
then Subaru stomps as any attack from Beatrice would kill Frisk permanently.
Again, why do you think the first thing he will try to do is kill Frisk when both sides would be open to talk it out? "Is will to kill" doesn't "will definitely and absolutely try to kill". In actual battle, Subaru would have no chance of winning, to begin with. Frisk needs to win just one time and they can just pull Omega Flowey on Subaru.
