Find the first non-recurring character in string
The code is too convoluted and unreadable for such a simple task


seems is a dictionary where the values are (first index, occurrences) pairs.  That's an unconventional data structure.  You'd be better off with two separate dictionaries.
seems is a weird variable name.  What does it mean, anyway?
Why is the index = len(string) statement necessary?


This solution is less cluttered, and more clearly expresses the idea that you are counting the characters, then finding the first unique one.

from collections import Counter

def first_uniq_char(s):
    counts = Counter(s)
    return next((i for i, c in enumerate(s) if counts[c] == 1), -1)