The Sura Al-Fatiha and the Sura Al-Ikhlas are sister suras in my opinion because they help us to delineate clearly those who need to be maintained and sustained and He who is self-maintaining and self-sustaining. In the Sura al-Fatiha, Allah is referred to as the 'Maintainer of all beings'('Rabil aalameen') and in Sura al-Ikhlas Allah is referred to as 'Absolute, Independent, Self-Sustaining, Self-Maintaining'('Allahu samad').
The 'beings' in Sura al-Fatiha refer not just to human and other living beings but also to all beings in the entirety of creation, such as the Universal Intellect and Universal Soul as identified in philosophical Ismailism.
According to a famous hadith of the Prophet Muhammad: The first being created by God was the Intellect ('aql). In philosophical Ismailism, Universal Intellect was the only being to issue, by a process of origination through the Divine Command or Divine Will, from the Absolutely Transcendent God, and everything else in creation is an emanation from Universal Intellect.
In more recent times the above concepts have also been described by the 49th and 48th Imams of the Shia Ismaili Muslims:
"Of the Abrahamic faiths, Islam is probably the one that places the greatest emphasis on knowledge. The purpose is to understand God's creation, and therefore it is a faith which is eminently logical. Islam is a faith of reason."(Aga Khan IV, October 9th 2006)
"The creation according to Islam is not a unique act in a given time but a perpetual and constant event; and God supports and sustains all existence at every moment by His will and His thought. Outside His will, outside His thought, all is nothing, even the things which seem to us absolutely self-evident such as space and time. Allah alone wishes: the Universe exists; and all manifestations are as a witness of the Divine will" (Memoirs of Aga Khan III, 1954).
~ Dr. Nasser Hadi Velshi, Toronto, Canada