In Act 1, Scene 2, Othello mentions his royal lineage when Iago warns him that Desdemona's father, a powerful senator, will do his best to obtain a divorce for his daughter, suggesting that it would be on the grounds that Othello is an alien and of inferior social status. Othello replies:
'Tis yet to know--
Which, when I know that boasting is an honor,
I shall promulgate--I fetch my life and being
From men of royal siege, and my demerits [i.e. merits]
May speak unbonneted to as proud a fortune
As this that I have reached.
Othello does not say that he is a prince but that he was of the highest social status in his own country and suggesting that he is completely worthy of marrying a woman of Desdemona high rank. He does not like to boast, but he does not consider himself an inferior to anyone in Venice. This assertion is apparently intended to show the audience that the marriage between Othello and Desdemona is not unsuitable and should be as lasting and as binding as any other marriage Desdemona might have made.