If you are having a hard time remembering who's who just goggle H of D characters and noodle around until you find a good site that will trace all the relationships of the various families.
I too had a hard time last night trying to remember where the different characters fit into the story. I got the eyepatch guy (Aemond Targaryen) confused with Daemon Targaryen.
“All you have to do, I tell myself, is keep your mouth shut and look stupid. It shouldn't be that hard.”
― Margaret Atwood, The Handmaid’s Tale