Why is there always a Fledgling Vampire running around Riften before I even start any of the DLC related quests?

Cant help you there, but that sounds weird!

if you're under level 10 it's a glitch which more and more people have been reporting lately.

If you're above level 10, then that's your reason.

Good to know someone has answers!

Thanks for the reply.

I had started Live Another Life in Ivarstead and reached Riften at about level 3.

Must've been the bug.

One of my characters has had an ash pile in Riften since long before there was even a rumour about DLC, maybe the fledgling just turns up sometimes. Whatever it once was the guards killed it.

Must have