Why he says less around to me around others. But with me, alone he's chatty?

So, I want to say about 3-4 months ago, this guy was giving me all this attention and being overly friendly at work with me. And it's crazy, because our supervisor didn't really introduced me properly to the people who I was going to be working with. The only person, that she never was the person, that's shadowing under her. Other people, I either introduce myself to them, or them to me. Anyways, fast forwarding. So with the guy, I start assuming, that he was interested in me because how he was interacting with me, and finding excuses to come to my station to talk with me. So, things was going good, between him and I, until he asked the girl that's under the supervisor, to ask me to vacuum his floors. So she basically told me what he asked for. And I'm like, I'm not even done with my task. So, as I was walking upstairs to his work area. I ran into him, and he greeted me with a friendly hello and say thank you, then walked outside smh. So, I told him as he was passing by that I was going to have to contact our supervisor, to make sure that it was okay with her. To be continue...

Updates
8 mo
So fast forwarding I did just as that, and she was not having it. So she touched base with him, I told him basically that he was going to have to do his own stuff. So, he mentioned to me that she was going to talk to him, and tell him to keep his distance and say hello and keep it moving. So she said basically if I didn't sign you to that duties, then don't do it, and tell people no. Basically she said don't let people try to run over you. So, he kept away from me. And there was tension.
Updates
8 mo
Until he broke the silence, and decided to talk with me again. I honestly didn't care tbh afterwards I was pulling back from the situation and him. But there was a time that I supervisor mention out loud and said let me know if anybody is bothering you. And he said thank you. So it's like, why go out of your way to get my attention, just to make this crazy eye contact with me, then avoid me with others around. But want to talk with me in private. Like could it be?
Why he says less around to me around others. But with me, alone he's chatty?
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