The introduction of new characters

We are introduced with new characters and thereby get to know more about Mina, who is revealed as the fiance of Jonathan. She seems to be quite committed towards Jonathan and her relationship as she mentions about how she had been trying of ways to improve her writing skills so that she could be of help to him in the near future.
We are also informed that she is an assistant school teacher and has been recently working hard with her journals so as to improve her skills and be more dedicated.
Lucy, the newly mentioned character in the story turns out to be Mina's closest friend since childhood as we frequently see them writing to each other and sharing about every special things that had happened to them as if they are more like sisters than just friends.
Three more lead characters are introduced however, they are just characterized as normal ones in their introductory part in the story because all they do is confess their love one by one to Lucy. Moreover, the characters are revealed from a third person's view i.e. from Lucy when she writes about them in a letter to Mina.
However, she carefully describes each one of the men and about their specialities and about how they had approached to her hence describing their nature and stating that they have some kind of main roles as we read along.
We also get to know that Arthur is the one that Lucy prefers to be with amongst the three men i.e. Dr John Seward, Mr Morris and Arthur whose every ways had took her breathe away.
All the information are achieved through letters that that Mina and Lucy share with each other.