S.
ARI is not dominant at all...S definitely is.
ARI has simply thrown his weight around all these years as a wealthy guy and people have allowed money to shut their mouths. eg., The initial episodes with the truck-driver and buying out his truck.
Whereas, S has had to rely only on her own speaking/problem-solving skills to make the best of whatever life has dished out.
Nature gave her an already dominant and solitary nature, and experiences further honed it.
(Solitary, because S appears to be more of a loner...she worries about her family, but is used to fending for herself and does not like to nor need anyone on whom to lean. She may share some with R but it is a one off thing, not a daily heart-to-heart with friends or lovers.)
But ARI got a loving, affectionate nature that was just waiting for someone to love him so he could shower it back on them. Unfortunately that happened to be Tunveer with her false face. Even now he is very affectionate and easy-going.
He loves to share with a loved one...in fact, even earlier, when he and S were at loggerheads, he started to tell her about his inability to sleep without drinking (nightmares), but she had left the room.
He shares about the Sheik, participates is all her family functions, and genuinely cares about her family.
Jayne
Cricket
Anupamaa
