The arrival of Van Helsing! This character has seen almost as many appearances in popular culture as Dracula himself. Pay close attention to what he actually looks like and how he acts.
The end of chapter nine is a good place to take inventory of the cast of the story. All of the important characters have been introduced and their relationships to one another are set, though they will continue to change a bit.
Blood transfusion was a relatively new concept at the time _Dracula_ was written. Whether or not blood typing was an understood science, it is clear that Stoker was uninformed about it. This is just one of the things we will have to accept in order to get into the story.
We know a lot more about Lucy’s illness than any of the other characters. Remember, none of them have read Harker’s journal! When does Van Helsing suspect something unnatural? Why doesn’t he tell Seward of his suspicions immediately?