Is this grammatically correct?

"I was surprised by the similarities that arose between the young fictional girl and I."

or is it "...fictional girl and myself?"

Neither.

It should be ". . .fictional girl and ME."

The pronoun is the object of the preposition "between" -- so it must be the object pronoun "me."

thank you!

The grammatically correct option is "fictional girl and myself."

When choosing between the pronouns "I" and "myself," it is important to consider the role the pronoun plays in the sentence.

In the original sentence, "I" is used, which is a subjective pronoun. Subjective pronouns are used as the subject of a sentence or as the subject complement after a linking verb. However, in this case, "I" is used as the object of the preposition "between," which requires an objective pronoun.

The correct option is "myself," which is a reflexive pronoun. Reflexive pronouns are used when the subject and the object in a sentence refer to the same person or thing. Since the speaker is one of the things being compared (the young fictional girl and the speaker "myself"), "myself" is the appropriate choice.

So, the sentence should be: "I was surprised by the similarities that arose between the young fictional girl and myself."