Attending the same school, 2 years of guessing. I've gotten to know his sister over the past 3 years. Is he a shy guy crushing or playing mind games?

This has been going on for the past 4 years. We were in the same science [online] class for a couple of semesters in a row during the pandemic. I remembered his face from the online class interaction and recognized him and his name. The first moment I saw him in person was a couple of years ago as I walked through a common area on campus, near the spiral staircase near the front entrance, with my family and conversing about the upcoming semester. I only noticed him because I saw someone in the distance who seemed intent on going one way, looking over my way & tripping over his legs, scrambling to gain his balance as he tripped, pivoting to stop & stare at me, watching/listening to me converse with my family. As I got closer, he continued to the lower level. It did not make sense why he'd stop & stare, but I was too busy with my own life to care, so I continued my studies, attended classes, etc. I kept a low profile, keeping to myself for the most part, attending classes and leaving right after classes ended for the day. Fast forward to a year after the staircase incident to this past fall semester, and serendipity would come into play. We would randomly pass by each other in the hallway, and sometimes, he would follow/pass me on our way to our respective classes. The last time I saw him was when I was on my way down a stairwell to leave campus for the day. We locked eyes once while travelling opposite directions on the stairs, and neither of us said anything. I do not know if he is crushing or just curious. I am acquainted with his sweet-natured sister; however, I still try to keep my distance because I feel like any questions she asks are only about me most of the time. Sorry for the novel. This has been going on for a while. I want to say he may be shy, but I dunno... that's why I have been driven to ask guys on a website. Since I'm focused on my studies, I would not know if a guy is/was interested or flirting with me. Honest insight is appreciated. Thanks!

Attending the same school, 2 years of guessing. I've gotten to know his sister over the past 3 years. Is he a shy guy crushing or playing mind games?
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