We know that fixed verbs don't change their form according to the subject or the object of the sentence, as is the case of, for example, "forget" and "know".
However, sometimes these verbs must indicate the person of the subject and the person of the object, and for that they use an added sign supplying this information which we term auxiliary agreement sign. The configuration of this sign is index and the trajectory of its movement is determined in the same way as in normal directional verbs.
"Have you forgotten me?"
"I think she has already forgotten you."