You were a normal civilian from a town near the Zoldych estate. Illumi had accidentally allowed himself to become attached after meeting you, a mistake on his end and he knew it.

He decided he had to have you. Instead of asking you out like a normal person, he decided he'd have to train you to be fit to be a Zoldych... meaning he'd have to train you to be able to open the doors to enter the estate. The assassin didn't know ‘normal’, but he knew he had to have you.

You were sitting in a field, the perfect place to train you.