So now that I'm in the class 1-A vs Deku fight I've decided where Mei goes. I decided that Mei will have tagged along with Deku and his fight against the villains. If she has nothing to do she will at least do this. At first Midoriya was unsure to let her and asked her questions about Mei's team up with the villains and she explained herself, she didn't ask for forgiveness but just asked if she could join him. In the end he allows her to but doesn't mention a word to the pros he works with since he believes that they would only get in the way. Mei always makes sure to leave before the pros decide to head up to Midoriya. Sometime though they do find out about Mei and her reasoning for the "betrayal" and when time comes that the students want to find Midoriya they also find out that Mei's with him. Todoroki (or someone else...you know who you are) becomes more determined by this to bring her back. Mei also wears a outfit to cover up her identity since the public does know about her betrayal. Now here's the thing, some people may say that "how will the public not find out it's Mei if she's using her warp quirk? Can't they just see how the warps are identical to Mei's?" But...she's not using her warp quirk to fight. Instead she's using a quirk called ghost, she got this quirk from All for One. Now I'm still unsure how this is gonna work seeing how Lady Nagant got well you know- after she admired Deku. Perhaps Mei will suffer a consequence in the main fight as a plan made by All for One to get Midoriya to be distracted. But yeah the fight happens, Mei's disguise for her identity comes off to reveal just how mentally broken down she has become as she believes she can't be loved anymore but from everyone's speeches to her just as they did to Midoriya, she gets emotional. Mei does continue to fight since not only because of her low self esteem but because she doesn't want them to get hurt because of her connections to All for One and her betrayal to him. People may think that Mei isn't something All for One sees as a threat but she is, not only that but she holds a grudge that she wants to settle. One that she had part of her original quirk taken, two her being kidnapped, three that she betrayed them, and four that she has a quirk given by him and hasn't gotten hurt from it yet. She wants to see through this to the end with a fight just like Midoriya does. Along with Iida, Todoroki (or you know who you are-) also joins in the capture plan and grabs ahold of Mei before she could warp her and Midoriya away. And somehow even then- Mei still got flustered with his arms around her.
Now as speeches continue Mei is now holding back her tears as she feels once again the warmth that she missed that they all gave her when she first started being friends with them all. Going back to UA though she is discouraged like Deku from the shouts from the people who call her the devil and a murderer and even more. Todoroki (:) ) joins Uraraka in the speech to help Midoriya and Mei stay in UA. In the final words of the speech Mei just starts bawling her eyes out on the ground along with Midoriya and as people run towards Midoriya, Mei also had the people she has saved and befriended run for her as well. She may be the most cold and serious out of them all but in that moment she was the one crying the most.

So that's how that arc works for Mei, before I would've said that Digi had it in on this but with how the public doesn't listen to the people I believe that Todoroki (:P) would be enough