I was curious about the long term effect of fisting or even multiple fingers/larger toys in the vagina? I have what has been described as a tight vagina which I would imagine would be positive, however, I am entering into a D/s relationship with a Daddy that wants to eventually be able to fist my vagina. Since this is new to me, even having 4 fingers inserted caused me to bleed slightly for about 24 hrs. Basically, if he continues, and if the relationship ends and I want to return to normal intercourse, will my vagina be permanently stretched?

 The vagina is a muscular tube. It's stretchy and can expand enough that babies pass through it. I don't think a hand is going to do permanent damage anytime soon. Now, I am a fisting and large object aficionado.  I love it. You whole genital area will be swollen and tender for a few days after a stretching/fisting session. I've never had my partner(s) say that fisting has lessened the sensation during sex once it returns to normal.

That said you can do damage if you rush things. You can cause micro-tears - which it sounds like you are already experiencing. Make sure if you are experiencing bleeding that you care for the area carefully. You don't want to get an infection. I am not a Doctor so I can't diagnose your problem specifically. Tons of lube is not an option, it's a requirement. And if you have a small vagina as you say it may take a very long time to progress. Patience is paramount. Don't have him push, you need to do the leading. Some people love the stretching feeling (moi) and others don't. You'll need to make that decision for yourself, but as far as permanently stretched out? No, it's not going to happen.