"Sleepsong" by Secret Garden
feat. Cathrine Iversen

A lullaby the queen used to sing to her newborn son. It is full of love and is everything Emilie wishes little Adrien in his life. This sleepsong has veey meaningful to the plot lyrics. Why? You'll learn in the next part.

Some lines I want to draw your attention to:

♡ May you sail fair to the far fields of fortune with diamonds and pearls at your head and your feet
Adrien is an heir of the de Vanily's dynasty. His destiny is to become a king one day with "diamonds and pearls" in his crown and to come into the kingdom's fortune. Emilie wishes her son to live long (sail far) and to be fair.

♡ May you find kindness in all that you meet
Usually a palace isn't a place for kind people. To survive there, to climb the title ledder or to make a fortune a royal court is ready to do everything: to lie, to betray, to stab in the back, to sell themselves and many other dirty tricks they can do. Adrien is a kind-hearted ray of sunshine there. Emilie wants to protect her son from the harm.

♡ May there always be angels to watch over you, to guide you each step of the way, to guard you and keep you safe from all harm
Emilie is afraid to leave Adrien alone in this uneasy path, where he can be surrounded by liars. That is why he needs someone to guide him and guard him, someone to be on his side, a partner, a friend, a guardian angel.

♡ May you bring love and may you bring happiness, be loved in return to the end of your days
Love is the biggest gift from the Heaven. Emilie wishes Adrien to find someone he can love with all his heart and who will love him in return, so they can live their happily ever after.

A side note:
In this AU comics Emilie's singing voice is similar to Cathrine Iversen