Alright, I was originally just going with the warhorse, but my recent lack of net time has left me with time to think...Much like the time I had that led me to switching Chaos and returning to the light side of the Force. So, I have come up with three choices. I'm going to give you all a brief summary and I want you guys to vote for which you think is coolest. I know the choice is ultimately up to me so I don't want to hear any "It's up to you" crap. Just give meh sum imput!

1. RuneSteed: Fire/Break

A massive, black stallion clad in cobalt armor. Dark blue flames wreath the area just above his hooves and flame up with every step. Mainly serves to defend Runeknight, rarely attacking, and grants him a second break attack to use each turn.

2. Arc: Elec/Wind

A young dragon, about the size of a horse, with dark blue scales. Arc has a lightning breath weapon which he uses to fry his foes and can beat his wings to hurl objects and enemies around the battlefield. Mainly aggressive, Arc aids Runeknight in offensive maneuvers and sectioning the battlefield for tactics.

3. Currently Nameless Cutie: Elec/Recover

A petite sorceress dressed in sexy black and silver robes. She lends a feminine aspect to the RP, plus gives Runeknight someone to converse with and protect...A damsel for the knight. She aids Runeknight with powerful spells that harness the power of lightning and can use her magic to heal the Dark Knight's wounds. Mainly playing a supportive role, she only attacks as long as Runeknight is above 3/4th HP.
I say get the Runesteed. It works well and Albel's already whoring the first cute female ally. XD

But I still support Runesteed. Don't like the second idea so much; I think it's just because the idea of Runeknight having a sidekick seems so strange to me.
I voted for the horse for 2 reasons:

1. Defense is necessary (If the whole Twi Incident said ANYTHING)

2. DNRcross will be your powerhouse of electricity! It is a manly element!
Alright, here are my opinions on these three:

Runesteed: it would just be totally epic to see Runeknight riding his faithful steed into battle, but that's just my opinion on that. For the record, I'm not a huge Break fan, plus Runeknight's already Break-type himself.

Arc: Not too fond of the idea. First of all, its a dragon, which kind of contradicts Runeknight. After all, the knight is supposed to slay the dragon, am I right? Although Wind-types are my tied-for-favorite eype, the other being Normal.

Sorcerer chick: Might be pretty cool. Like Rune's liege or damsel, as you said. Although Rune of Vigor has done a pretty good job keeping you alive so far.

My personal idea: Pegasus, anyone? Basically your Runesteed idea, but with giant wings to make it a Wind-type instead of Break.

What's a knight without a horse? I'll tell you. LAME.

Besides, the fusion is important too. Arc would look like a cheap Drauchen BO, and the girl would just look like a cross.

Know what Runeknight merged with RuneSteed would be? A FREAKING CENTAUR OF DOOM.
The steed.

A dragon? Knights FIGHT dragons, not ally with them.
A damsel in distress? Meh. It might be good at first, but what then? A relationship between navi and SP?

But the horse... yes. A knight with a horse is win. And you can ride it, but the centaur-knight fusion would really be the show-stealer.
Wait... I thought they weren't supposed to have a main element.

Quote (DNR)

I voted for the horse for 2 reasons:

1. Defense is necessary (If the whole Twi Incident said ANYTHING)

2. DNRcross will be your powerhouse of electricity! It is a manly element!

I'm gonna imagine you didn't say that. *Shudder*

Horse. If knights didn't have horses, what would they do? Walk with their feet!? NO KNIGHT WALKS WITH HIS FEET! NO KNIGHT AT ALL!

Quote (Shuryou)

Wait... I thought they weren't supposed to have a main element.

Otherwise I might've registered a flaming bunny. :'D
I say Warhorse, It'll just make Runeknight all the more pwnsome.
Actually, they can, but they have to charge a turn to apply it to their attacks.

Also, I am not WHORING HER OUT, she's just friendly in a silly way XD

And finally, the horse. The others kind of fit, but seriously dood, RUNEKNIGHT NEED STEED
I voted for ALL THURIEE. XD
Because all sound really cool.
: D
I don't know annnything.
There's no fire-breathing warhorse option.

I refuse to vote.
I think that the girl would be best from a sratagy point of view...

if you get attacked by water, you could use her to have an elemental advantage...
But what's the FUN in that?
And if Zan gets attacked by Wood-types, the girl will phail.

Type advantages don't matter if you have an element. Even if you have an advantage, you'll always have a weakness to compliment it.

Quote (Shuryou)

Wait... I thought they weren't supposed to have a main element.

Danno, answer. >_>
Well, let's look at the rules here...

Quote ()

Attack (Your SP attacks an enemy you command for the listed damage of it's level. Attack can either be your SP's Element, or Normal element. For an Elemental attack, you must spend one of your SP's actions to charge.)

That's the only mention of Element in the SP rules. Not very conclusive. However...

Quote ()

Subtype Ability (Your SP uses its subtype ability. This ability acts just as a normal subtype ability would, with the exception that your SP can use it through your Navi. (IE: A Break-type SP could add Break to its master's attacks the same way Break-types add Break to their attacks.) For recovery SPs, this can only be used with your SP's attack stat, with the healing amount calculating like buster damage heals.

THAT'S the only part that mentions subtype. Nowhere in the rules does it say ANYTHING about registering element OR subtype.

But seeing as how you would need them both registered in order to actually use them, I'm gonna say that yes, SP's have element. (Note that having element does nothing for a SP until they reach level 3, when they can actually have the actions to charge their attack with their element.)

Now, I think the real question should be, are SP's restricted to being the same element as their master? I'm thinking no, but I can never be too sure.
Shuryou, I'll PM Twi for clarification, I want my flaming bunny back. D':
So, it seems fairly unanimous toward the horse, eh? The reason I was thinking something else is that technically I have other ways of making a horse...I.E. SigAttk or maybe even a GMO if I could get away with it. Hmm, as my net is still spotty, I'll wait until maybe Friday and then decide and post my app.
I stand by my claim that a Fire/Wind-type Pegasus would be absolutely win beyond any type of win ever seen anywhere before.