Maldeclone A and C's Links
Every year, Maldeclone C (as well as F) send Rin a few Christmas presents every year, as their emotion-based personalities cause them to still care about the murderer. Rin doesn't know that they're behind it, and thinks that another killer who really likes them is instead. Or perhaps an evil version of Santa.
While Rin likes Maldeclone C slightly more than the rest of the Clones, the link between the two still has to be [REDACTED] for now.