Lakshmana is part of the Mariyada Purshottamm, or The Perfect Man personified by Rama, by his unswerving loyalty, love and commitment to his elder brother through times of joy and adversity alike. He is an Invincible warrior committed to virtue and the service of his brother. He never covets the throne of Ayodhya, nor hesitates from joining his brother in exile, even though he does not have to.
Lakshmana serves Rama and Sita reverently during the exile, building them a home in the forest and devotedly standing guard during the night, and accompanying them on tiring journeys and long passages of lonely forest life without complaint or care for himself.
When Rama kills the deer, even as he is dying, Maricha cries out in Rama's own voice, crying for Sita and Lakshmana to help him. Although Lakshmana knows that Rama is invincible and beyond any danger, Sita panics and frantically orders Lakshmana to go to Rama's aid immediately. Unable to disobey the frightened and panicky Sita, and genuinely beginning to fear for Rama's safety, Lakshmana goes out to search for him. He however uses his mystical power to draw the Lakshmana Rekha or Lakshmana's Limit, a perimeter line across the hut that Sita must not cross, and no other being save Lakshmana or Rama may enter uninvited. If any intruder enters, it will be instantly killed.
Sita however, out of compulsion of religious duty and compassion for a poor brahmin, who is actually the disguised Ravana, crosses the line to give him alms. Thus Ravana is safely able to seize Sita.
The Lakshmana Rekha has become a metaphor in situations where a certain limit must not be transgressed by human beings in no circumstance whatsoever.
Ramacharitamanas, the wildly popular North Indian rendering of story of Rama, does not feature the Lakshmana Rekha story in the Aranya Kanda. Neither does the original, the Valmiki Ramayana. However in Lanka Kanda of the Ramcharitmanas, (35.1) Mandodari rebukes Ravan on his boisterous claims of valour by hinting that his claim of strength and valour is shallow for he could not even cross a small line drawn by Shri Rama's younger brother Lakshmana.
Hanuman, the mighty vanara follower of Rama, flies all the way across the length of Bharat to reach the mountain in the Himalayan ranges. Unable to find the magical herb, and knowing there was no time to waste, Hanuman uses his incredible might to lift the entire mountain and bring it to Lanka, the scene of the battle. The magical herb is retrieved and Lakshmana is revived.
While he is generally considered to be rather short-tempered when compared to Rama, Lakshmana is also considered an important element of Mariyada Purushottama, displaying great courage and presence of mind when Rama becomes distraught, angry and desperate over the loss of Sita — in an uncharacteristic display of desperation, a furious and almost hopeless Rama, not knowing of Sita's fate or whereabouts, is suddenly about to fire a weapon capable of bringing vast devastation of life; Lakshmana stops Rama, calms him down, explains to him that the world is not responsible for their separation from Sita, and consoles and encourages his righteous brother, while giving him support and strength to keep looking for her.
When Sita's jewels were given back by Sugriva to Rama, Rama lamented Sita's absence, remembering the jewels she used to wear. Lakshamana then gave Sita's toe-ring to Rama in order to aid his grief. What was implied is that he has never looked beyond the toe of sita. As a great respect to the discipline followed by Lakshmana, the great Tamil poet Kamban made the statement on his character that "a great person never looks desiringly upon another's wife."