The former child actor, who portrays Bran Stark, aka the Three-Eyed Raven, on the hit fantasy drama series, enrolled in England's University of Birmingham in 2017 to study mathematics and music, but the crowds which gathered and gawked at him wherever he went made Isaac think twice about continuing to pursue his higher education.
Recalling moving into a student apartment, he tells Britain's Esquire magazine, "I walked in and this girl just looked at me. And I was like: 'Hello,' and they were like 'Hi!' I went to get some more stuff and when I came back, they'd had like, a flat (apartment) conference to say, 'Oh my god, what the f**k is going on?' "
"We went for dinner and they didn't actually say anything until, eventually, one of their mates was like: 'So apparently you're in 'Game of Thrones'?!' "
"From there we went to some awful club night, and it was just... a massacre."
Isaac admits he was overwhelmed by all the attention he received, even though he expected there to be some fanfare at first. "I knew people would be excited and there'd be a bit of fuss. But I could not anticipate the chaos," he says.
Things only got worse for the star when his campus address was published online.
"I couldn't walk out of my halls without having to take a selfie," he remembers. "Eventually I got assigned a campus police officer. There were so many tweets. And because your (college) email is public domain, I got like, billions of emails from people going: 'Hi, Three-Eyed Raven!' I was just trying to find out where my next lecture was."
The crazy turn of events also made it tough for the actor, who turns 20 next week, April 09, to make genuine friends and allow himself to let loose.
"I had the nicest flatmates. But it made it quite difficult to make friends," he shares. "I don't think I'll ever be able to have a normal university experience, which is kind of sad."
"I couldn't relax and go out and have a drink or get drunk or whatever, because if I did someone would be like: 'I saw Bran and he was all f**ked up.' "
"My ex-girlfriend came up to visit and we just sat in my room for a week."
Isaac eventually withdrew from school to focus full-time on acting, and "Game of Thrones" co-creator David Benioff is confident the teen will find further success in whichever career path he chooses.
"If he wants to be an actor, he's already proven he has the chops," Benioff explains. "But we could easily imagine him teaching in a university somewhere, or writing the Great English Novel."
The eighth and final season of "Game of Thrones" premieres on 14 April.