Friends of Clementi's said that he'd never had a girlfriend in high school and had never come out as gay. He was always focused on his role in the school orchestra, said friend Rob Righthand.
"He was one of those kids who never had a girlfriend and never had a boyfriend. You just thought he wasn't open for dating or anything like that," said Righthand.
"He was an incredible violin player. That was his No. 1 thing," said Righthand.
Clementi's suicide has shaken Rutgers, Gregory Blimling, Rutgers University vice president for student affairs, told ABC News.
"This is a highly rare occurrence," said Blimling. "In my 36 years as an administrator in student affairs, I don't think I've ever seen anything like this."
There is evidence that in the days following his roommate's alleged spying on him, Clementi reached out to a gay website to complain. The e-mails, written by someone identified as "cit2mo" and first cited by Gawker.com, describe a situation that mirrors Clementi's -- the videocam spying by a college roommate.
Since Clementi's death, a message reading "in loving memory" appears next to the handle "cit2mo."
Cit2mo seems particularly upset that comments after the incident sympathized with his roommate for having to share his room with a gay person.
"People have commented on his profile with things like 'how did you manage to go back in there? are you okay?' and the fact that people he was with saw my making out with a guy as the scandal, whereas I mean come on... he was SPYING ON ME...do they see nothing wrong with this?"
Clementi's roommate, Dharun Ravi, also 18, and another Rutgers student, Molly Wei, have each been charged with two counts of invasion of privacy.
But a friend of Ravi's said he believes it was just a prank.
"He's very, very open-minded," Michael Zhuang said. "If it had been a girl in the room it wouldn't have been any different."
A Facebook memorial group created in honor of Clementi already has tends of housands of members and hundreds of comments remembering the college freshman.
One of Tyler's friends, Courtney Ayukawa, posted to the group's wall, "I will always remember everything from our preschool's Halloween party to your amazing musical talents. When you picked up the violin and began to play, it was as if everything just paused until you put it down again. We will never forget you Tyler. May you rest in peace."
Strangers have also contributed to the memorial page, one writing simply, "R.I.P from a stranger."
People from around the world have used the page to speak out against online bullying, writing, "Tyler, I'm sorry that this World couldn't accept you as you were so wonderfully made," and "If we are to truly honor Tyler's memory, we must all work to show light to all gay youth in despair."
Police said Clementi and Ravi had known each other only for a few weeks. The school year at Rutgers began on Sept. 1.
A Twitter page that appears to have been operated by Ravi but has since been taken offline shows messages in which the accused student takes credit for the alleged videotaping of Clementi.
Ravi apparently tweeted about his roommate on Sept. 19 before live streaming Clementi's sexual encounter, writing, "Roommate asked for the room till midnight. I went into Molly's room and turned on my webcam. I saw him making out with a dude. Yay."