The scribe who straightens out Kempe's first, corrupted version of Book One and works with her to produce Book II is often—but not always—identified as Kempe's confessor, Robert Spryngolde. Literally almost nothing is known about him historically, except that he was a priest at St. Margaret's parish in Bishop's Lynn. As one smarty-pants has put it, "This is an issue where the scattered and contradictory evidence resists any definitive judgment" (source). In other words, we have no real idea who "wrote" The Book of Margery Kempe.
We do know for sure that Kempe relied on Master Robert's friendship, counsel and support, especially at times when her credibility in the town was at low tide—which was pretty often.
Robert makes appearances at key moments in the text, like when the Guild Hall catches fire and he brings the sacrament out to combat it (I.67.202), or when Kempe returns to West Lynn after her series of arrests (I.55.175). He's also totally grouchy about Kempe's wanting to travel to the ship to see her daughter-in-law off to Prussia (II.2.270), since Kempe is now old and has an injured foot. Robert just can't even when Kempe returns from Prussia without having got permission for travel (II.10.292).
In all of his interactions with Kempe (at least the few we see in the narrative), Master Robert appears appropriately stern. But it's clear from his good advice and concern for his spiritual charge that he genuinely has her best interests at heart.