The story available in Puranas about incineration (burning) of Manmatha (God of Kaama) by Lord Siva is as follows:
Indra and the gods are suffering at the hands of the demon Tarakasur, who cannot be defeated except by Shiva's son. Brahma who advises that Parvati woo Shiva; their offspring will be able to defeat Taraka. Indra assigns Kamadeva to break Shiva's meditation. To create a congenial atmosphere, Kamadeva (Manmatha) creates an untimely spring (akAl vasanta).
After he awakens Shiva with a flower arrow, Shiva, furious, opens his third eye, which incinerates Manmatha instantaneously and he is turned into ash.
Compared to Srimad Ramayana, Puranas can be considered as very recent.
The decimation of Manmatha was told differently by Sage Valmiki in his Srimad Ramayana.
Sri Rama and Lakshmana proceeding with Vishvamitra sojourn in a hermitage at a place, where River Ganga and River Sarayu are confluent. There they have seen a hermitage of sages with contemplative souls, and who are practising supreme ascetics for many thousand years.
On seeing that merited hermitage Sri Rama and Lakshmana are highly pleased and enquired as whom hermitage belong to? Sage Viswamitra replied as follows: (Bala Kanda 23 Sarga 11-15 Slokas)
कन्दर्पो मूर्तिमान् आसीत् काम इति उच्यते बुधैः | तपस्यंतम् इह स्थाणुम् नियमेन समाहितम् || कृत उद्वाहम् तु देवेशम् गच्छन्तम् स मरुद् गणम् | धर्षयामास दुर्मेधा हुम् कृतः च महात्मना ||
"Sthanum was practising ascetics at this place. When Love-god was with his body wise men used to call him Kama, the passion, that Love-god with his naughty intent braved god of gods (देवेशम्) at this place. The God of gods (देवेशम्) was returning after his marriage along with his followers, namely the Wind-gods (मरुद् गणम् |) , and that great soul disapprovingly roared at Love-god.
अवध्यतः च रुद्रेण चक्षुषा रघु नन्दन | व्यशीर्यन्त शरीरात् स्वात् सर्व गात्राणि दुर्मतेः
"And Rama, the wrathful eye destroyed the lewd-minded Love-god making all his limbs to fall down from his body."
तत्र गात्रम् हतम् तस्य निर्दग्धस्य महात्मनः | अशरीरः कृतः कामः क्रोधात् देव ईश्वरेण ह ||
"There the body of Love-god is evanescent when that great soul burnt it down, and by the anger of that god of gods, Love-god is rendered as a bodiless entity."
तस्य अयम् आश्रमः पुण्यः तस्य इमे मुनयः पुरा | शिष्या धर्मपरा वीर तेषाम् पापम् न विद्यते ||
"This merited hermitage thus belongs to Sthanum and, oh, brave Rama, these sages abiding in virtue are his disciples at one time, thus sin is unverifiable with them.
While narrating the above story, Sage Valmiki uses the word Devesham (देवेशम्), which were interpreted by many as Lord Shiva.
But according to Valmiki Ramayana, which closely adopted the Vedic Pantheon, Devesham (देवेशम्) refers to Lord Indra. In Aranya Kanda he was praised as vibhuDeswaram (Chief of Gods).
Further, the Devesham in this story decimates the Manmadha with roar - hum kritascha ( हुम् कृतः च) like Sage Kapila decimates 60,000 sons of King Sagara to ashes.
And, the Devesham in this story was returning after his marriage along with his followers, namely the Wind-gods, when he decimated Manmadha to ashes but not before his marriage.
Wind-gods (मरुद् गणम् |), were the sons of Diti, the wife of Sage Kashyapa, and step mother of Lord Indra.
Diti seeks for a son to kill Indra because Indra and other gods have killed her sons in the battle after churning Milk Ocean. But Indra, being her stepson arrives at her place of asceticism, with view to destroy that Indra-killer. On a fateful day when Diti failed to maintain the procedure of vow, Indra enters her womb and dissects the foetus into seven fragments. At the request of Diti, Indra blesses the seven segments of her foetus to become sapta marut gaNa-s, The Seven Wind-gods.
So they started moving with Lord Indra but not with Lord Siva.
Hence, in my view the actual eliminator of Manmadha was Lord Indra but not Lord Shiva as commonly believed.
Is it correct?