i dont think youre evil for not giving tenna to mettaton but the way people justify that& talk about it is what throws me off. you can do bad things in games even when thats what the game is trying to warn you about. both undertale and deltarune (not that sure about dtr, but ut definitely does) warn you against starting to treat the characters as meaningless, breakable toys at your disposal yet you can not explore all of the game and TRULY understand the story its trying to tell either by DOING the bad things, which the game hates you for, or WATCHING SOMEONE do it, which undertale ADDRESSES through floweys dialogue, and encourages others to do and record that content. so. without the content in the genocide route or weird route, would undertale/deltarune be what it is now? no. are you a bad person for taking those? i dont think so. you wanted to see the game in its full and appreciate it. as long as you dont stray from the lesson it teaches, do what you want.
NOW, the mettaton part. treating mettaton as a person who needs help will have you giving him tenna. EVEN THOUGH undertale warns you about how just for the sake of more content, treating characters as lines of code can lead to detachment and not taking the story seriously anymore, i think its okay to keep tenna in your castle town. OKAY. but that doesnt mean you shouldnt respect mettaton's issues (loneliness, dysphoria, probably a fear of going outside etc) as it is representation and real things that people experience. trying to justify forsaking a seemingly healthy coping mechanism with "i want tenna to fix his relationship with my dealmaker" is where i start to question you. "king wants a jester" is where i start to question you. same thing for "it makes noelle sad" and, what i believe to be the most important, "it makes the mikes depressed".
i have seen people say shit like "oh sorry metts, you gotta cope with ur dysphoria on ur own LMAO, i didnt have a crt when i was strugging amd turned out fine, i just have to see the spmtnna makeout scene so transition on ur own" and THATS WHERE THE PROBLEM STARTS!!! thats like doing the weird route and saying "sorry elly but i coped with manipulation, harrassment and soul crushing trauma from someone i trusted without a red soul's mercy saving me from it! you gotta break outta there yourself noelle! its honestly not even that bad" under a screenshot of her suffering.
people dont try to justify weird or genocide routes, or even slightly petty things (i have never seen people try to justify drinking alphys' juice in front of her!) but when its mettaton you gotta act like that?
for the kings jester part? i doubt you cared about king before it gave you an excuse to keep tenna, and saying mettatons well being is less worthy than kings OCCASIONAL ENTERTAINMENT is worse than not saying anything. "noelle gets sad" she gets NOSTALGIC. and she gets nostalgic over so many things i dont think not watching tenna again will be much pain for her.
for the MIKES. i know people hate understanding mikes especially battat but you HAVE to acknowledge, BATTAT ISNT HEALTHY!!! tenna isnt HEALTHY FOR BATTAT
They spend so much of their life wearing a costume they HATE, forcing their best friends to do the same constantly, LIVING IN A DREAM WORLD, REFUSING TO GET OUT OF THEIR COSTUME, to the point they dont have too much of a personality to express when out of it, and what they tell themself to relieve themself of the guilt of what they do to their friends and self? "its for tenna". battat needs to be seperated from tenna to face themself, and THEY LITERALLY SAID TENNA TREATS HIS EMPLOYEES LIKE GARBAGE!!!!!
conclusion, i can understand doing "bad things" in videogames but i dont get how doing mean things to other characters is passed off as "oh i wanted to see what happens" but when its a trans person struggling with intense dysphoria everyone just has to talk about how mettaton can cope with it himself and isnt actually having it that bad and should just get on with it. i am not saying you are bigoted for keeping tenna im just saying we should address the larger pattern here.