Rune images: After the boss fight and before the rune attaches itself to you, it communicates with you and shows you several images. The images show men in Harmonian armor/garb looking for something in a forest, and you get an image of the unity Rune in that same forest. The unity rune moved itself (as True Runes can do) but the Harmonian army kept chasing after it. It fled again and again, but couldn't escape. It eventually came to the caves in the Orbel Mines where you found it, and the rune seems...afraid. It lets you know it wants to keep away from those "bad men", or Harmonia, and it needs friends to do that. It senses you will be its friends, and entrusts you with its power.
To note: All true runes are sentient and have a will of their own. This rune, so far, seems almost childlike in its desire for friends, and its fear of the Harmonian army.
The Unity Rune governs the powers of Friendship and Betrayal. Due to its nature of friendship, it's going to be 'friendly' and let you each tap into a different part of its powers. So Jon, who has water and flowing, might want it to be an offensive rune, where Mike and Kerri who have offense might want a healing rune. Sarah, who is going to be berserk 24/7, is going to want it to be a passive rune and give an ability and not magic. Maybe you want it to be a type of command rune, where it lets you do a ton of damage in battle as a melee attack. Whatever you want. The one thing is, it's going to be a little different for everyone, as friendship means something different to everyone.
When deciding on what your unity rune does for you, I'd look over the below possibilities, and/or the abilities of the runes in the book. Being a true rune, your rune will be better than a 'basic' rune, but a tad weaker than a 'whole' true rune (yours is split into nine parts, after all). so look over the ideas when you get a chance, run your ideas by me and I'll be happy to tailor your rune to you specifically.
Unity Rune Possibilities:
Offensive:
1. Backstab: [Unity Magic Grade × 5] + 1d12 damage. Target: One enemy. Teleport behind one enemy, and stab him in the back.
2. Get him! [Unity Magic Grade × 10] + 1d12 damage. Target: One enemy. Entire Party surrounds and beats up one enemy mercilessly.
3. Distortion [Unity Magic Grade × 10] + 1d12 damage. Target: All enemies. The unity runes ‘breaks’ a bond between worlds, and the energy distorts the enemy. Chance of enemy getting sucked in to the closing fissure. (Roll a 1d12; if a 1 or 2, enemy is killed).
4. Traitor’s Torment: [Unity Magic Grade × 15] + 1d12 damage. Target: One enemy. Ghosts of traitors past haunt the target, assaulting his/her mind.
Support:
1. Call of Heroes: Revives a fainted Ally with (Magic grade x 5) HP. Target: One Ally.
2. Preventive Medicine: When used, no ally can be hit by any status conditions for this battle. Target: All allies.
3. Call to Arms: All allies are guaranteed to hit this round, with (Magic grade) added to the melee damage rolls. NOTE: Regardless of initiative, this spell always goes first. Target: All allies.
4. Protection: Nullifies all attacks on party this round. Target: All allies.
Healing:
1. Power of friends: [Unity Magic Grade x 5] + 1d12 HP restored. Target: One ally
2. Strength of friends: [Unity Magic Grade x5] + 1d12 HP restored. Target: All allies
3. Wonder of Friends [Unity Magic Grade x 10] + 1d12 HP restored. Target: All allies
4. True Friendship: Heals all HP for all allies. Target: All allies
Sword of Unity:
1. United we stand: Adds 1 damage to your melee damage roll for every three friends (aka stars of destiny) you have. Target: Self.
2. Human Shield: Take the blow for any wounded ally. NOTE: This spell always goes first, regardless of initiative. Target: Self.
3. Final Shot: Target: One enemy/self. Put all of your HP and MP into one final, desperate attack. Always hits with the formula: (Remaining HP + Remaining MP + Weapon grade + any attack bonuses) x Your level. User then falls KO.
4. Self Sacrifice: Sacrifice half of your HP to fully restore the rest of the party. Heals all status, KO, and all HP (but yours). Target: all allies.