A "little angel" is a warm way to describe a child or person who seems sweet, kind, and well-behaved. It can also be used playfully or sarcastically when someone is not as innocent as they look.
All of a sudden, your little angel turns something quite unfathomable. Source: Internet
Although seven-year-old Hanna displays the full spectrum of autistic behaviors like not vocalizing and destructive temper tantrums, she’s Daddy Alex’s little angel and Mommy Suzette’s devil in disguise. Source: Internet
In letters to third parties, she vented her impatience, referring to him as a "child," a "little angel", a "sufferer" and a "beloved little corpse." Source: Internet
He’d lost a fair amount of weight after birth (in part because my little angel peed twice in the OR right after they weighed him) and though he wasn’t in the danger zone, the doctors were a little nervous. Source: Internet
The cover drawing shows a boat (the Sant'Angelo), on the left end of which stands a little angel wearing a priest's hat and playing the violin. Source: Internet
One comment pointed out Mr Al-Mohammad's "fearful expressions just before he breaks into laughter", while another said "the laughter of this little angel is much more powerful than the noise of that bomb". Source: Internet