The Kingdom of Serenia is a location that is exclusive to the comics and appeared in Issue 42: Milly's Secret. It is the home of Princess Iris, Cordelia, and her daughters, Villania and Rospunda, and Count Neropulos. The kingdom is known for its terrible storms.
The kingdom is ruled by monarchy, however, the kingdom's king and queen are deceased, and thanks to the Winx, their long lost princess has returned to the throne.
It is safe to assume that the kingdom was once a free from dictatorship. That is, until the death of the king and queen, and the disappearance of the kingdom's only heir, young Princess Iris. After these unfortunate events, the kingdom fell under the dictatorship of Count Neropulos. He ruled with an iron fist and the citizens came to loathe the Count. Meanwhile, the princess was kept under constant house arrest and to serve as an indentured servant to Cordelia and her daughters, unaware of her rightful lineage to Serenia's throne.
It can be assumed that the fauna is relatively the same as on other planets and kingdoms. The most notable are Princess Iris's white birds who kept her company during her days as an indentured servant and who lead her and the Winx to the palace where the debutante ball was being held.
Due to the kingdom's fearsome storms, the grounds are often muddy and therefore is very lush and green. Trees, grass, bushes and cattails can be seen. There appears to be very little flowers, quite possibly due to the strong winds from the storms, in which they are unable to withstand.
#42: Milly's Secret
The Winx are driving in one of Serenia's terrible storms, trying to reach the Dark Lake Academy but end up getting lost (thanks to Stella). They try asking for directions at Cordelia's Estate, their maid, Milly answers the door but does not know where the academy is.
Seeing as the group is lost and cold, Milly lets them inside to warm them up with tea. Lady Cordelia questions the strangers Milly had let in and sternly reminds of her chores to must do.
There is a debutante ball being held tonight at the royal palace. And the Winx convince a hesitant Milly to attend because she deserves to have fun, especially on her birthday. After putting on a disguise, they all head for the ball. There, Milly falls in love with Prince Hargon and when she unmasks herself after their engagement announcement, the attendees are appalled to see the stunning resemblance to their late Queen Aldesia. They all learn that Milly is really their long lost Princess Iris.
It is revealed that after the death of the king and queen, the princess had also disappeared, and Count Neropulos came to rule with his iron fist. By luck, the kidnappers accidentally reveal themselves, none other than Cordelia and daughters Villania and Rospunda. The Count "arrests" them and sends them to the dungeons to "await trial".
After learning what they had done, Milly still wants to know of her heritage and wants to ask Cordelia about it. She, her fiance and the Winx head for the dungeons when they overhear that Cordelia and her family were in cahoots with Neropulos. They are planning an escape but are captured by the Winx and Hargon, respectively. The kingdom now has their rightful ruler and no longer have to withstand Neropulos' dictatorship.
With Milly finding her happy end, a staff from Dark Lake Academy finally locates the Winx and proceeds to take them to the academy, while getting a small snippet of what the Winx had been up to during their time of absence.