"Yes, he used to date a friend of mine, Alyssa."
My face remains neutral, though the reminder of them together makes my jaw tick and my fists clench. 
"Right," I say, dryly and trying not to look too fazed by this. 
"Yeah, things didn't end well between them. But don't worry, I don't hold a grudge toward Matteo or anything," she chuckles. "Alyssa just needs to get over it, really."
The bigger part of me wants to ask what the fuck she's talking about, to know what happened between them since Alyssa always brushes it off and Matteo doesn't voluntarily speak to me anyway.
But if I ask, I'll seem too nosy and I don't want to raise any suspicion. 
But I can't help myself. "Get over what?"
The girl just stares at me for a few seconds, before she parts her lips. 
"He cheated on her."
The words register, but at the same time, they don't.
"What?"
"He cheated on her," she repeats and shakes her head. "It was so sad. In her own bed, you know? With one of her closest friends."
Matteo... cheated on her? 
But why would she go through all the trouble to join us on trips and family gatherings if he did a horrible thing? 
Why did she act so casual about it, when I know how sensitive she is, and it for sure broke her heart? 
Why did she never tell me?
With one of her friends, in her own bed.
I'm going to kill him.
When I don't say anything about it, the girl continues. "She's in your class, isn't she? Alyssa?"
It takes a few moments for me to gather my scrambled thoughts. 
"That would be correct."
"Oh, what a relief," the girl sighs and shakes her head. "Everyone told Alyssa it was a stupid plan, but knowing you're her professor makes you unreachable," she chuckles.
I narrow my eyes at her. "What plan?"
She shouldn't be discussing this with me, and I have no idea what she's doing here in the first place. Just to see if I'm Matteo's brother is odd. 
"After she found out he cheated on her, she wanted to hurt him just as badly," she whispers and seems to be in agony about all that happened. 
"She knows about your strained relationship with Matteo and how it'd affect him if he knew she went for you. She wanted to use you in her ploy for revenge."
That can't be true. Alyssa wouldn't do that. Not to me. 
Though she did insist on going on vacation with me, she became very interested after she broke up with Matteo.
But no, not my Alyssa. She wouldn't use me like that. 
"And she told you all of this?"
The girl nods. "Yeah, she did. She was out for revenge and to hurt your brother, so I came to check to see if she succeeded and to warn you about her. But if you're her professor, I'm sure she wouldn't cross that boundary and be so immoral about her ridiculous setup."
She would be, though.
She was. 
"Why come to me now? When did this happen, the plan?"