probably animation speed not set to 0
"The problem with that is, the array changes dynamically. I am basically making a friends list inside Construct 2. So lets say I have 100 friends on my list, which is stored in a database, and I only created 50 frames in Avatar, then it would break that system."
I would only load the images on usage. You can store the images as data URI (string) in an array (I guess) and then just load it when you display it. This way you only will need as many frames as the number of avatars you display simultaneously.