Lupa

Lupa is the immortal wolf who trains demigods in the ways of Rome. She trains Roman demigods at the Wolf House then sends them to Camp Jupiter where they can join the legion.

Caretaker of Remus and Romulus
Remus and Romulus were the twin sons of Mars and Rhea Silvia who were thrown into the River Tiber at the command of their great-uncle Amulius. They were saved by a great she-wolf who nurtured and raised them as her own young. Having grown strong under her guidance, the twins would go on to destroy Amulius and establish the city of Rome.

The Lost Hero
Lupa contacts Jason in his dreams to warn him about Gaea inadvertently. She also calls Jason their "Saving grace" and curls her lips in a smile as if she just made a joke. Jason, not knowing his last name at the time doesn't see the humor. It isn't until he learns who he is that he understands what Lupa had meant. Later, when Lycaon attacks Jason and his friends, he makes a reference to Lupa, saying that soon Lupa would have to think twice before attacking his pack.

The Son of Neptune
According to Percy, she promised him that he would see Annabeth again if he succeeded in his quest. She apparently taught Percy to sharpen his senses, the "homing senses" that had led him south. She also told Percy his name after Hera took his memory. It is also said that her pack slowed down the army of Polybotes on their way to Camp Jupiter. However, she did not interfere with the final battle at the camp as it is not her way.

Appearance
She is described in wolf form with beautiful chocolate red fur and eyes as silver as mist. She is also described as being very tall, taller than any human. In Jason's dream, she was seven feet tall.

Personality
Being a Roman Goddess, Lupa is harsh and judgmental towards people, mortal and god alike. She only respects the strong, as any demigod who she judges to be weak is devoured by her wolves. She doesn't seem to care about the hierarchy among gods, as she confessed to be indifferent to Hera while she was imprisioned in The Lost Hero (though she acknowledged her importance and the consequences of what would happen if Jason's quest failed).

Despite her militaristc personality, Lupa has a softy side. For example, it's implied that, while strict, she has enough laidbackness to occasionally crack a joke, as seem when she called Jason their "saving Grace" (a reference to both his surname while the tv series). She can also be a loving mother, as Percy claimed that she frequently tells her role in Romus and Remulos fate, implying that she still is proud of them.

Powers
For now, Lupa hasn''t make any personal appearance, but it's implied that she's quite powerful. For exemple, being the wolf goddess, she has control and divine autority over all the wolves in the world, exept the lycanthropes, who are subjects of Lycaon (explaining their rivarly). it's implied that shes very strong and skilled in combat, as Percy (having been trained by her) knows what she is capable of doing, to the point of becoming horrified when Reyna claimed that she and her pack aren't enough to defeat Polybotes and his army (though this might be due to the Doors of Death being opened at the time, thus preventing the Giant army from being permanently killed). she also has limited Hypnokinesis, enough to contact Jason in his dream.

Trivia

 * Interestingly, as leader of the Roman Camp, she still knew where Jason Grace was and was able to contact him in a dream. And yet Chiron, the director of the Greek camp, has not made any mention of being able to contact Percy, though possibly because it was Juno/Hera's Roman counterpart, that switched the two leaders, its likely that she informed Lupa beforehand as to not harm Percy for being a Greek demigod. It could also be due to Lupa being a goddess.
 * It is also possible that Chiron was not able to reach Percy because he was supposedly in a deep sleep, and he only woke up in June, whereas Jason woke up in late December.
 * Her name, Lupa, is the female form of the Latin word for wolf (lupus). Lupa is therefore literally translates to She-wolf.