He/She/They want any sort of relationship. After that is set up they'll exploit it for whatever it seems good for. Whatever you might go for - money to buy her baby back from an orphanage, money for passage over here, money to pay some fine so she can leave the country, money for botox for her mother so she can extend her working life another 2 weeks.

The changes in profile picture are interesting. Are they the same person?

The one thing you know for sure is that it's not legitimate. She's not a long-lost cousin, she's not the child of your uncle who served in WWII, she hasn't fallen in love with your unquestioned brilliance, wit and charm. (She would, but she hasn't been exposed to them.)

But you might email her back, expressing thanks for her offer but explaining that you are looking for marriage and not just another casual, empty relationship. See what happens.