Are there any canine companions that I can pick up along the way? I'm only 12 hours in and I have Veronica with me at the moment. She seems cool and interesting.

Vulpes, Antony, or Regis (or any Khan companion, really). Me and Vulpes would be bros.

Marcus!
Is it because I had the weirdest crush on him since Fallout 2?
Nope nope, not at all *hangs head in shame*

Maybe Manny Vargas I always felt kinda sad that Boone just ignores him, i'll bring along Boone and be all likehttp://alltheragefaces.com/img/faces/large/%5Bcensored%5D-now-kiss-l.png

You can get Rex, the King's cyberdog.

How do I get him?

I like the ones we have, but I'd love to see specific House and Leagion NPCs.

Most of all, I'd like to rock out with a full party, FO2 style.

Well I think obvious companions for those two would be Victor (since he's been helping you along the way and could easily go help you out again if House told him to) and Dead Sea.
While Dead Sea has a job to do at Nelson once you kill the leaders at Folorn Hope he doesn't really need to oversee Nelson anymore, another Decanus can take over (Alexus) and then you could ask Caesar if you could be given a legionnaire to help you out.
A decanus is not too high ranked, not a specialist but not just the everyday grunt either. A decanus is capable, balanced.
Dead Sea has performed his job and his current task is... Wasting his potential.
And if Caesar asks of him to accompany the Courier then he will gladly oblige.

Dead Sea would never accept the Courier siding with anyone but Legion, so there is no such choice for him other than that, you can on the other hand, through his personal quest, decide the fate of his future in the Legion, of whether he will become a frumentarii, a centurion or praetorian. (Centurion for battle provice, Frumentarii for stealth and deception and Praetorian for servitude and protection of you.)

I don't really see any other Legionnaire fit for the task of companion other than him.
Vulpes, Lucius and Lanius are all too high ranked.
Aurelius already has a job.
Severus has a job.
Otto has a job.
Canyon Runner has a job.
Anthony has a job.
Cato has a job.
Karl has a job.
Lucullus has a job.
Only named legonnaire without anything to do is Dead Sea once you kill off all the Forlorn Hope officers.

Talk to the King about Rex and you'll get the "Nothin' But a Hound Dog" quest. Following it will get you Rex as a companion pretty soon in the quest and completing it will give him an upgrade depending on the choice you make in it.

Nice, thanks.

The only option for him to become is a Frumentarii, even at that he would need to impress both Caesar and Vulpes, since only the stealthiest, cunning and quick thinking Legionnaires become one - Dead Sea seems too much like an up front hands on kind of soldier. Centurion and Praetorian are both ranks above Decanus, and in order to get them a Legionnaire must earn them through the blood of fallen foes so the only way he'd get them is through severe bloodlust. A Praetorians are also specially selected to guard Caesar as they are the most elite fighters in the Legion and are trained by Lucius so he'd need to impress both to earn this rank - after achieving that of Centurion.
That'd be one drawn out quest with plenty of options and NPC levelling up - not bad actually.

Well he is the only humanoid fully Legion-companion.
He needs a long quest line and lots of character development.

Of course to become a Praetorian, he'd also have to challange and kill another praetorian in 1v1 combat. That'd be interesting to see.

I really liked Sunny Smiles' personality, wish she could have been a companion.

What do you mean only humaniod, are all the Legion androids

I think she was originally meant to be one.

I should probably have worded that differently than "humanoid", I meant human.
Cass doesn't like Legion.
Veronica doesn't like Legion.
Arcade doesn't like Legion.
Boone doesn't like Legion.

The only companions that don't care are a robot, which doesn't care about any faction, a dog, which again doesn't care about any faction, just The King, Raul which is basically like "eh" about every choice and Lily, which doesn't seem to care about anything but you.

So Dead Sea would be the only human companion that is actually "for" Legion taking over.

I honestly think I like adventuring on my own, I get into quarrels with my companions for stealing my kills.

If I could have a fully-fleshed out Vulpes as a companion (quests, dialogue, all that), I'd be a happy camper, even if I had to play Legion to get him.

Mr. House

I would have Ulysses just because it be so cool walking down the route 95 with I cowboy outfits and are 44 magnum pistol I can see it now.

Radroach

The couriers brain.

Jules in north vegas square,he knows the wastes is a cool bad ass and i bet has some good stories to tell by the campfire, plus he packs .44 handloads in his magnum,before any patches in vanilla game passing a high survival skill check with him was the only way to get them.

Agreed! I thought Silus would be a good candidate, if you rescue him from NCR captivity. He's a centurion, but he probably has also pissed Caesar off by not dying, his quest could be regaining the favour of Caesar.

Meyers would also be a good addition, if you decide to elect Primm Slim or invite the NCR.

That emo kid in the Khans? Though he'd be pretty unbearable on a long-term basis.

By the way, there's a pretty good Sunny Smiles companion mod over at the Nexus, complete with dialogue and a perk. You guys should check it out.

Wouldn't he be kind of a burden dragging him and his apparatus along? Can't shoot, can't carry and always bellyaching to be plugged in.

I would like to have the former Great Khan and retired NCR 1st Recon, Manny Vargas. He'd surely kick some serious ass with his background. It would be like having a better version of Boone, without the depressing demeanor.