Person Behind Character
Zacharias Werner (1768-1823) German romantic poet	Does a dual with Goethe of a cycle of seventeen sonnets in competition for Minna's charms.
Minna Herzlieb (1765-1839)	In 1807, she came to Weimar, where she met Goethe, who presented her with some sonnets; it has been argued that she may have been one of the models for Ottilie.

In Elective Affinities, the architect, see: Goethe’s affinity table, was an old pupil of the Captain who, beginning in chapter fourteen, became a main character in the novella, supervising and guiding a number of architectural projects on and about the estate, and to a certain extent became enamored with Ottilie, and in this sense a combatant to Eduard and his interest in Ottilie. [1]

Person behind character
To a certain extent, as Goethe said "lived every word of my Elective Affinities", and noting that Goethe was an architect, at times, in the course of his own existence, it can be argued that some of the character of architect embodied aspects of Goethe himself, although not in the sense as did the Eduard character.

In the winter of 1807 to 1808, Goethe fell in love with 18-year-old Minna Herzlieb (1765-1839), the "foster daughter" of the printer and publisher Karl Frommann (1765-1837); the product of this was the cycle of seventeen sonnets written as a dual with Minna's other admirer, the fomantic poet Zacharias Werner (1768-1823); who seems to have been the character behind the architect character of the novella, who attempts to win the affections of Ottilie in competition with Eduard. [2]

Alternatively, in his 1811 autobiographical notes, Goethe wrote: [3]

“As to persons who this year called on me in Weimar, I find the following mentioned: Engelhard, architect from Cassel, on his way to Italy. It was asserted that he had been the prototype of my artist in the Elective Affinities.”

See also
● Architecture
● Architectural thermodynamics

References
1. Goethe, Johann. (1809). Elective Affinities (architect, 34+ pgs). Cotta.
2. (a) Hollingdale, R.J., Goethe, Johann. (1971). Elective Affinities (“Introduction”, pgs. 1-16). Penguin.
(b) R.J. Hollingdale – Wikipedia.
(c) Carl Friedrich Ernst Frommann – Wikipedia.
(d) Zacharias Werner – Wikipedia.
3. Goethe, Johann. (1901). Annals or Day and Year Papers (translator’s introduction by Charles Nisbet; Contents: Annals by Years, pg. xiii; 1807-1811, pgs. 144-183; elective affinities, pgs. 156-57, 168, 177-78, 181). In: Classic Memoirs, Volume 32. Colonial Press.

Further reading
● Engelstein, Stefani. (2008). Anxious Anatomy: the Conception of the Human Form in Literary and Naturalist Discourse (Architect, 4+ pgs). SUNY Press.