ZORO'S EARING
MARKING HIM AS CLAIMED
PENELOPE'S HAIRPIN
MARKING HER AS CLAIMED
PENELOPE'S ENGAGEMENT RING
Zoro's nickname for Penelope is Nel. Its one that was never used by anyone else before, something he specifically choose since he knew that her normal nickname, Pen, had come to resemble pain and heartbreak.
Since Zoro has a tendency to take a nap literally anywhere, Penelope developed the habit of putting pillows under his head and covering him with a blanket in the winter. Zoro naturally doesn't bother to put the pillows away when he wakes up. The staff find it adorable and since Zoro will often return to the same places to nap, have taken to just leaving the pillows where they are. So now the entire estate has random pillows scattered about in abnormal places and the servants have a list of the most likely places to find the young master if he is required and missing.
Zoro has taken to purchasing random books he thinks Penelope might like and hiding them in random places around their homes. That way she'll always have new reading material at hand.....some of these books may or may not also be banned or considered of an inappropriate nature for ladies of the Ton.
They've come up with code phrases for everything, including when one of them is at the point where they are about to damn society and pounce the other one. This code of course changes constantly so watchful people, like his Aunt, don't catch on.
Zoro loses about 90% of them because Penelope will storm off to find a stool or chair to stand on so she can get on his level and then he just bursts into laughter. He's started retaliating by getting down on his knees sometimes so he's not the only one breaking into laughter. But truthfully they don't often come to full disagreements since they established good communication at the beginning of their relationship. So more often then not they talk it out before it gets to an argument level.
Neither of them had any desire to sleep in separate rooms. So while they maintain different quarters for their personal effects, they take turns sleeping in each other's beds.