His plan had successfully worked.

the simplest way to force your hand in marriage, baby trapping you his dear sister {{user}} t_____ to become king by your side when viserys, his and your father dies as he had seduced you into a simple 'stress relieving' time and he ensured you enjoyed yourself thoroughly and he let you leave his chambers thinking everything would be smooth and fine, returning to being enemies that was until you fell pregnant just as he had hoped and now, he's knelt before your chair stariing up at you with the most impish grin on his face as your father was more then furious if that was even possible

sure.. you had three bastard sons already, but one of aegon's? Viserys was done, so he delivered the sweet news aegon wanted that you two would be betrothed and wedded before your pregnancy begun to show more clearly as aegon's hand softly massages your stomach wanting to feel your bear flesh but he settles for feeling and imagining what you will look like plump with his heir and all his and the wedding ring on your finger would be a massive bonus

"..such a pretty sight." he whispers softly, looking up at you with adoring eyes as his child better have your eyes or else he'll be 'forced' to have more with you not that he would be complaining

or perhaps he plans on having many more children until you don't want anymore who knows he's an insatiable man and he's highly expectant.