Who is Ivan Arnoldovich Bormenthal from Heart of a Dog and what is their importance?

Ivan Arnoldovich Bormenthal assists Philip with his medical practice and research. Bormenthal is younger than Philip and idolizes him. He claims there is no better physician and Europe, and he feels honored to work with him. Bormenthal assists with the surgery that eventually has the effect of anthropomorphizing Sharik. However, as it becomes increasingly apparent that Sharikov is unable to coexist in Philip's house, Bormenthal begins to advocate for killing Sharik or at least reversing the operation. Philip rejects these ideas at first before finally deciding to reverse the operation.