Lets say I go out and see someone wearing a cross, do I have to repent for seeing it?
No you do not, no one ever had to, no one will ever have to. Book people have always been around, and allowed to wear crosses, since the beginning. It is one of the things they do. You do not have to repent for merely seeing one.
please forgive the reference and the tone You are not a vampire. Your eyes do not burn since you saw it. Your life must be so hard if you believe this kind of thing. Who on earth told you such nonsense ?
following downvote If you wanted someone to point to a hadith that could in a very off sense forbid to see (not look or contemplate, just see) a cross, you should just have asked "What hadith can be interpreted as an interdiction to see a cross?". There are none. But if you look well enough, you will find one that you will interpret as an interdiction to see a cross. For instance, you could repent for not trying right away to convert the person wearing that cross. Or see the cross as a kind of idolatry, and repent for not destroying it. I am sure you will come up with something. But no, there are no hadiths about this.