This is an AU explanation of how Faramir came to be attired as he is in this picture, which I certainly regard as AU!
Faramir, Captain of Gondor, Captain of the White Tower, and Captain of the Ithilien Rangers, subdued a tremble as he opened the package. His aunt, Ivriniel of Dol Amroth, was a dear and kind lady; but he had lived in fear of her gifts since childhood. Even now, he could not help but shudder at the memory of a certain blue satin tunic with blue velvet leggings; how foolish he had felt wearing the things, and the relief when he could finally undo those blasted silver lacings.
Oh, no. He was surely undone beyond all help! Faramir gingerly lifted out several garments which would have surely been acceptable, sturdily made as they were, save that their colors included a garish orange as well as proper Ranger-green.
The orange trim on the hood was bad enough, but an orange mask? Sweet stars above, orange leggings? Faramir supposed he should be grateful that the boots were a sensible shade of green-brown.
He found a letter bound with his aunt’s seal and opened it. My dear child, read the graceful script; Imrahil tells me that the men of Ithilien are sadly low on supplies. I have sent some wine and treats for our brave Rangers, and fresh raiment for you. Keep warm, sister-son, and the Valar’s blessing on you all.
Exclamations from several of his men told Faramir that they had opened the crate Ivriniel had marked for the Rangers. Anborn and Mablung praised the virtues of pickled herring as they pulled out jars containing the delicacy. Young Herendil ogled one of the bottles of pale, yellow Lossarnach wine as their supply officer, Beor, efficiently counted them.
“Praised be your lady aunt, Captain,” said Hathol, Beor’s assistant and the company’s tailor. Suddenly inspired, Faramir beckoned Hathol to his side.
“Good Hathol, I would give this raiment into your stores in return for darker clothing, in particular the leggings”, Faramir proposed.
To his surprise, Hathol threw up his hands and backed away. “No sir, you’ll have to keep them. I have naught else that would fit you; you are the tallest of us all. And if your lady aunt learns that you scorned her gift, she may send no more , to you or to us. ‘Twould be bad luck to refuse the clothing. And the lads take such pleasure in the victuals. Please, Captain; she sent us cranberries this time!"
Hathol’s love of cranberry-apple sauce was legendary.
Faramir looked around him. Other Rangers had heard Hathol’s words and now pulled such woebegone faces that he had to crack a smile. “Very well. I shall be a bold robin rather than a raven, but only for a day or two, to honor my aunt’s generosity."
Relief replaced rue in his men’s eyes. Faramir fingered the appallingly bright orange leather caplet. It would be a time for strange sights in Ithilien, if the Moon-land’s Captain were to walk so oddly attired.
Perhaps his new clothing could at least frighten the Haradrim, or other trespassers.
Author's Note: Faramir did have a semi-canonical aunt who actually was named; Ivriniel, older daughter of Adrahil of Dol Amroth and sister to Faramir's mother Finduilas; mentioned in the Dol Amroth family tree in HoME XII: The Peoples of Middle-Earth.