The Rightful Heir of Slytherin (Year 6 - Book 1)

Prologue

The year is 1988...

As Professor McGonagall sat with the Dumbledore in his office, talking about prior events, the two are suddenly hit by a wave of emotion followed soon after by a cry for help. Neither knows from whence it came but both are alarmed by it and immediately try figuring out what had just occurred.

They are in the midst of discussing it with one another when the other teachers come rushing into the office all at once. Amongst them is Patricia Rakepick, the professor for Defence Against the Dark Arts. She'd only agreed to join the staff following Dumbledore's request and had planned to merely use her position as a means to an end but of all the professors, she seemed bothered by the events the most.

Dumbledore: Did you all experience the same?

One by one, the professors each recounted what they had experienced, much of which was the same but as Patricia spoke McGonagall experienced yet another episode. This time, it was accompanied by a vision. In it, she saw the emblem of the Slytherin house followed by a vision of a large Snakewood tree deep inside a ruin. Beneath the tree's roots, she saw a small cavern that opened as she neared it. Heading in, she's led by a faint glow in the distance to an even larger opening with fern and overgrown weeds coating every visible surface. However, what catches her eye is a coffin in the centre of the otherwise empty room. 

Walking towards it, she's surprised to see a young female inside. Visible through the glass top, she looks every bit alive as any other living being despite not moving or showing any actual signs of living. After a few attempts at opening the coffin end in failure, McGonagall decides to look around and that's when she sees it. Carved into the wood are the words; Altissima mei poenitet. 

Seeing them, Minerva repeats each word audibly as she tries to capture what exactly they mean. When the last word leaves her mouth, however, the words change revealing a much longer text.

Here lies Cassandra Sarea Slytherin, cursed to forever be chained by love, ever evading death and my waiting arms. To any who finds my beloved child, if it be within your power, free her from this cursed box. If not, then I ask that you protect her from harm and keep her away from those that may seek to harm her, especially those cursed muggles. 

Cassandra my child, I won't ask for your forgiveness but I do ask that you not allow my actions to prevent you from living should you finally break free from this bond. Live my child, as your mother would have wished of you. 

Your Loving Father,

Salazar Slytherin.

Minerva could hardly believe her eyes. As she continued staring at the message, however, the world around her vanished in a flash of green that cleared to reveal the concerned face of Dumbledore. Seeing him brought tears to her eyes though she knew not why. Rubbing her eyes to prevent them from falling, she barely managed to calm herself down before the first question arrived.

Dumbledore: You saw something, didn't you.

Opening her mouth to reply, Minerva found it hard to so much as produce an audible sound. As she fought through the struggle, fresh tears began falling from her eyes, catching everyone in the room by surprise.

McGonagall: It's...It's Slytherin.

Snape: What?

Severus seemed as though he was about to snap but as McGonagall continued to breakdown, his features turned from one of impending anger to compassion. Seeing her in her current state reminded him of something from his past and it brought tears to his own eyes.