Well, I'm working with this definition of angels:
329 St. Augustine says: "'Angel' is the name of their office, not of their nature. If you seek the name of their nature, it is 'spirit'; if you seek the name of their office, it is 'angel': from what they are, 'spirit', from what they do, 'angel.'"188 With their whole beings the angels are servants and messengers of God. Because they "always behold the face of my Father who is in heaven" they are the "mighty ones who do his word, hearkening to the voice of his word".189
330 As purely spiritual creatures angels have intelligence and will: they are personal and immortal creatures, surpassing in perfection all visible creatures, as the splendour of their glory bears witness.190
Christ "with all his angels"
331 Christ is the centre of the angelic world. They are his angels: "When the Son of man comes in his glory, and all the angels with him. . "191 They belong to him because they were created through and for him: "for in him all things were created in heaven and on earth, visible and invisible, whether thrones or dominions or principalities or authorities - all things were created through him and for him."192 They belong to him still more because he has made them messengers of his saving plan: "Are they not all ministering spirits sent forth to serve, for the sake of those who are to obtain salvation?"193
