sur son dos

on one’s back

→ sur
phrase Rare #39,005
on one’s back Can also mean that someone is constantly bothering or nagging them, as in "to be on someone’s back."
FR: Il a porté son sac sur son dos pendant toute la randonnée.
EN: He carried his bag on his back for the whole hike.

Il m'a porté sur son dos jusqu'à l'hôpital.

He carried me on his back all the way to the hospital.

— La Famille Tenenbaum (2001)

Elle portait sa petite sœur sur son dos.

She carried her little sister on her back.

Le colporteur portait un gros paquet sur son dos.

The peddler was carrying a large bundle on his back.

Elle portait un bébé sur son dos.

She was carrying a baby on her back.

Puis j'ai vu une fille porter sa sœur sur son dos.

Then I saw a girl carrying her sister on her back.

— Thirst, ceci est mon sang (2009)