Marinette and Alya discuss Lila and her lies. This takes place during season 4 and is currently canon compliant. It makes sense that Marinette and Alya would have this type of conversation once Alya knows Marinette is Ladybug.

"Alright. I think it's time you tell me about Lila. I know she lied about being Ladybug's best friend. Clearly because you're sitting here, but is there more to it than that?" Alya asks Marinette while they sit on her couch after laying the twins down for bed.

Marinette sighs, "There's so much more. She's done nothing but lie to everyone from the moment she came to our school."

"Are you sure?" Alya asks.

Marinette gives her a glare, "Yes I'm sure. She started with the Ladybug stuff and then admitted to me that she just tells people 'what they want to hear.' She's a liar through and through and I'm tired of her lying to you and all our friends."

Alya sighs, "I'm sorry I never believed you, girl. But if you say she's been lying, I believe you now. I understand why you couldn't prove it to me before too. You couldn't tell me you knew she was lying about Ladybug because you are Ladybug. But what else has she lied about?"

Marinette grumbles, "What hasn't she lied about? Her trips have been a hoax. She has been akumatized into Volpina during one of her trips to Achu. Remember Heroes day?" Alya nods. "That was Lila's doing. She somehow got akumatized into Volpina, caused the illusion of an akumatized Ladybug, and then Hawk Moth took the akuma back and turned himself into Scarlet Moth somehow. But Cat Noir and I are both sure that Volpina is the one that made the illusion."

Alya shakes her head, "I can't believe she has been lying to us. She seemed so nice."

Marinette sighs, "That's not even the worst of it, Alya. Cat Noir and I are pretty positive that she is willingly getting akumatized to help Shadow Moth. The akuma that turned her into Chameleon was after me first. Because I was angry with Lila after a confrontation in the bathroom, but I was able to calm myself down. Somehow it found its way to Lila, who was happy just seconds before. There's no way she became akumatized because of anger. She was happy after threatening me."

Alya looks at her in concern, "How did she threaten you?"

Marinette sighs again, "She said she would turn all my friends against me and make sure I never get close to Adrien unless I do what she says and be with her instead of against her. She gave me until the end of the day and I turned her down and she declared war against me."

Alya gasps in outrage, "How dare she! Marinette, you know that no one could ever turn me against you. I'm here for you, always."

Marinette smiles, "I know that, Alya. My friends know me better than that, and Adrien wasn't going to fall for her lies either. He knows she's a liar too."

Alya's eyes widened, "He does?"

Marinette nods, "Yeah. I sort of confronted Lila in front of him out of jealousy as Ladybug. That was when we first met her and I expressed that I didn't appreciate her pretending to be my best friend. I had never met her before she came to school that day." Marinette flushes, "It wasn't my best Ladybug moment, but Adrien has been cautious around LIla since and has told me he recognizes her lies too. He held me back from confronting her though."

Alya looks puzzled, "Why would he hold you back? She needs to be exposed."

Marinette shrugs, "He thinks it'll make her worse or something."

Marinette scoffs, "Her lies and threats to you are already too much. She almost got you expelled. I'm sorry. I like Adrien, but he has a lot to learn. I'm not just going to sit around and let Lila lie to all our friends. We have to do something about her!"

Marinette smiles, "I agree, and I have tried. But the class won't listen to just me."

Alya nods her head, "Then we will have to take her down together. Collect all our facts and show the class so they can't refute it. I'm sure Adrien and Nino will help us once they understand the full scope. I doubt that Adrien would have stayed out of it if he had known that Lila threatened you."

Marinette gives her a small smile, "You think so?"

Alya nods, "I know so." She grabs the remote off the couch, "Now, let's watch a movie and then tomorrow we will plan Lila's downfall together. We'll call the boys and let them in on our plan to take the liar down."

Marinette smiles wide, "Thank you, Alya."

The two settle into the couch for the movie, needing the distraction from the Lila topic for at least one night. Tomorrow they can plan her demise together.

A/N - I am not going to include Lila's downfall. These are conversations that are somewhat canon compliant and including the downfall of Lila will take away from the canon. I like to imagine that the girls have talked about her and are planning what to do. But I guess we will find out in season 5.