My 20 year-old son has been an Eagles fan since he was a little guy. We always get Sunday Ticket so he can see the games at our house so we all watch the Eagles with him. During his teen years, his reaction to a loss or a bad play or whatever became so violent that the whole house started to care more about the Eagles than any other team because we hated what it did to him.
So why keep buying the Sunday Ticket? Well, that's on my wife. She's the step mom who will nearly kill herself to make the two boys from my first marriage happy... Ironic since watching the eagles caused so much grief over the years.

I grew up an Oiler fan, but they disappeared into the Titans so I had no team.

My oldest son likes the Patriots so we watch them too, but when the two played at the same time I always watched the Eagles to help keep my crazy son calm.

It became impossible to not become a fan.

When the Patriots and Eagles played in the Super Bowl that last time, even the Patriot fan in the house cheered for the Eagles.

Incidentally, my previously hot tempered son is a lot more calm than he was when he was younger. He's married with a family of his own but we'll still see him every week for the Eagles.