From the catechism:
The angels in the life of the Church
334 In the meantime, the whole life of the Church benefits from the mysterious and powerful help of angels.201
335 In her liturgy, the Church joins with the angels to adore the thrice-holy God. She invokes their assistance (in the funeral liturgy’s In Paradisum deducant te angeli. . .“May the angels lead you into Paradise. . .”]). Moreover, in the “Cherubic Hymn” of the Byzantine Liturgy, she celebrates the memory of certain angels more particularly (St. Michael, St. Gabriel, St. Raphael, and the guardian angels).
336 From its beginning until death, human life is surrounded by their watchful care and intercession.202 "Beside each believer stands an angel as protector and shepherd leading him to life."203 Already here on earth the Christian life shares by faith in the blessed company of angels and men united in God.
Footnotes:
201 Cf. Acts 5:18-20; 8:26-29; 10:3-8; 12:6-11; 27:23-25.
202 Cf. Mt 18:10; Lk 16:22; Ps 34:7; 91:10-13; Job 33:23-24; Zech 1:12; Tob 12:12.
203 St. Basil, Adv. Eunomium III, I: PG 29,656B.
I know that we all have a guardian angel, but I am not sure how they function. Clearly they cannot alter our will, but perhaps they are meant to protect us.